Exactly this
We need to define what 'to justify' means for this:
To have a good reason for something.
So for something to be unjustified means the opposite:
To have no good reason for something
If death threats are unjustified there can be no reason for them. No 'but'
There are several posters who have repeatedly said something along the lines of 'read my posts, I've said it's unjustifiable to make death threats, but...' who can't grasp how this is faulty thinking.
This is the basic first step in reasoning. If your argument defies reason it can't be valid.
The prostestors in their argument were unreasonable as there is no justification for death threats. They have not used reason to conclude that offence justifies death threats ( that isn't possible). They have used faith.
Faith by definition is:
strong belief in the doctrines of a religion, based on spiritual conviction rather than proof.
Believe in and practice your particular faith. That's your right in this country. You have no right to expect anyone else to believe in or practice your religion.
If you break the law in the name of your religion you have still broken the law.
The prostestors issuing or supporting the issuing of death threats should have faced due process for what they did. They are the unreasonable, unlawful party in this. There is nothing unreasonable or unlawful in the actions of the teacher. There is no 'but the teacher shouldn't have'.
Anyone who continues to say a variation of 'the teacher was wrong in some way' is by definition justifying the death threats because they have used that 'but' You cannot reasonably say, 'I don't support the death threats against the teacher but the teacher should have known better.' It is not a valid statement.