You assume wrong!
Mandela himself wasn't simply supporting violence in terms of legitimate resistance, but actively supporting terrorist groups such as the Provisional I.R.A who had no popular support from the people and also always had a democratic route.
In short Mandela was a terrorist. Not a liberator.
If you believe that 'one man's terrorist is another man's freedom fighter', then you are arguing that something being terrorism is really just a matter of opinion.
One perspective with a claimed equal opposite perspective. This kind of thinking easily gives rise to False Balance aka bothsidesism, False Equivalence, False Dichotomy and so on. These are logical fallacies.
If 'terrorism' is, as you say, really just a matter of opinion, then other opinions are available and just as valid.
So, what is the view of various Sovereign Governments, European Union and courts on Hamas?
Since 2001, the Council of the European Union has adopted a "common position" and a regulation to combat terrorism.
In 2014 after Hamas contested their designation as a terrorist organisation, the EU's General Court found the EU's terrorist designation had been "based not on acts examined and confirmed in decisions of competent authorities but on factual imputations derived from the press and the internet". Furthermore, the General Court asserted that, "The court stresses that those annulments, on fundamental procedural grounds, do not imply any substantive assessment of the question of the classification of Hamas as a terrorist group within the meaning of the common position."
Unsurprisingly, Hamas took this as validation of their own acts of terrorism which they claim was supported under international law as "resistance".
In 2019, the European Court of Justice overturned the ruling of the General Court. The ECJ asserted below:
"The Court of Justice, sitting as the Grand Chamber, sets aside the judgment of the General Court of 4 September 2019. It finds that the General Court erred in law in ruling that the statements of reasons relating to the retention of Hamas on the lists annexed to the acts at issue should – in the same way as the acts themselves, which contain a general statement of reasons – have been signed by the President and the Secretary-General of the Council. In addition, those statements of reasons were adopted by the Council simultaneously with those acts, to which they were inseparably attached, and their authenticity has not been validly challenged."
And:
"...that the Council produced documents demonstrating that the statements of reasons were adopted simultaneously with the acts at issue signed by the President and the Secretary-General of the Council, to which they were inseparably attached, and that Hamas has not put forward any evidence that could call into question the fact that the text of the statements of reasons that were notified to it and the text adopted by the Council correspond perfectly. Since the authenticity of those statements of reasons has not been validly challenged by Hamas, the Court concludes that the action brought by Hamas must be dismissed in its entirety."
So, the European Union was AND remains correct to designate Hamas NOT as a so-called "resistance movement", but as a TERRORIST organisation. Especially since Hamas did NOT argue against the authenticity of the CoE's statements of reason that led to this designation in the first place!
That leads us to the designation of Hamas as a terrorist organisation by, aside from the EU, Sovereign States such as the United States, United Kingdom, Australia, Paraguay, New Zealand, Canada, Argentina and others.
It surprises nobody that Israel designates Hamas as a terrorist organisation as well.
In 2023, "The United States welcomes Germany’s decision to ban activities supporting Hamas" and asserted that "Hamas is a dangerous terrorist organization, which engages in barbaric actions and has compounded and perpetuated the suffering of the Palestinian people at every step of this crisis".
And:
"Authorities in Germany's most populous state, North Rhine-Westphalia, have outlawed a Palestinian organization that promotes Hamas and calls for the eradication of Israel on Thursday".17 May 2024
In the United States, the so-called "charity" Holy Land Foundation For Relief and Development was accused of funding a terrorist organisation - Hamas. On 24th November 2008, their five leaders were convicted of 108 counts. Other so-called charities including Holy Land Foundation (HLF), Islamic Association for Palestine (IAP), and Kind Hearts were also shutdown by United States authorities for funding a terrorist organisation - Hamas.
The "one man's terrorist is another man's freedom fighter" slogan implicitly holds (paradoxically) that ‘terrorism’ is inherently bad while ‘freedom fighting’ is good, and that labelling an act freedom fighting precludes it from also being viewed as terrorism. Making it a nonsensical statement, naturally, whilst serving as motivation for terrorist groups to manipulate as many people as possible to believe they're not terrorists.
But it is supporters of terrorist organisations themselves, their fellow travellers and their sneaking regarders who actively attempt to push that flawed cliché. Usually to people who have not had to think very much, if at all, about the problem of terrorism.
Hence, websites have a legal duty and requirement to observe the law. That means passing information on to the relevant authorities, deleting comments and, yes, banning accounts who attempt to push support for terrorist groups, explicitly and/or implicitly, overtly and/or covertly.
It would seem that some advocates of the "one man's terrorist is another man's freedom fighter" school of thought have a bit of a problem.
As Randy Borum, Directors of Psychology of Terrorism Initiative said:
"When we abandon the cliché that one person’s terrorist is the other’s freedom fighter, we can better understand (or adopt) Jenkin’s definition that: “One man’s terrorist is everyone’s terrorist”.
Hamas is a terrorist organisation.
By the way, all opinions are NOT equal. Indeed, those opinions suggesting, could be interpreted as support and explicit support for terrorist groups are ILLEGAL under the law.