No, you are wrong.
Even The Guardian article, that YOU have sent, says this:
"British nationality law allows the home secretary to remove a person’s UK citizenship if doing so is deemed to be “conducive to the public good”. However, it is illegal to revoke a person’s nationality if doing so would leave them stateless."
Javid was aware that Shamima only had until she was 21 (she was 19 at the time, still a teen) to claim citizenship in Bangladesh, but had no way of claiming it, but still used this as a way of legally stripping her of her citizenship, which was effectively a legal loophole - something the Tories are great at - but that in real terms and ethically, is illegal.
The state minister of foreign affairs of Bangladesh, Shahriar Alam, said in a statement to the British media just days after Javid’s announcement that Begum was not a citizen of Bangladesh and would be denied entry to the country.
Again, from YOUR Guardian article:
"A two-day hearing in the case in November heard that Begum was still considered by MI5 as a national security risk because although she had travelled out as a minor, she had “aligned” with the terror group.
Lord Pannick QC, representing Begum, said she was unable to put her side of the case properly from al-Roj detention camp where she was being held. He told the court she would be at risk of physical harm if she spoke by mobile phone to her British lawyers."
Once again, the hands of the Supreme Court were tied; they acknowledged that Shamima had no way of having a fair trial whilst her life was under threat in a detainment camp, but they have no choice but to take MI5's word that she is still classed as a "risk," but MI5 do not need to provide any further reasoning or evidence, because again, their evidence of who is and isn't a threat cannot be disputed by the courts, amounting to another legal loophole, but in real terms, they knowingly deprived her of her right to a fair trial, which is illegal.
From the Human Rights Watch website:
"The Court ruled that [Shamima's] due process rights are indefinitely suspended until she can play “an effective part in her appeal without the public’s safety being compromised,” but gave no indication of when that might be and left the decision in the hands of the government. This leaves Begum stuck in a detention camp in northeast Syria where thousands are held without any legal basis, in conditions so dire they amount to inhumane treatment or even torture."
Essentially, Shamima is a pawn in the government's own agenda, and there the hands of the courts are tied.
"The UK Government should heed growing calls from security experts, UN officials, and human rights groups, and immediately repatriate Shamima and the other British women and children. To turn its back on them is not only a legal and moral aberration, but a long-term security risk. Leaving them in detention camps leaves them vulnerable to radicalization and the dire conditions can serve as a recruitment tool. If we have learnt anything from the last 20 years, it’s that our security is never served by undermining human rights." www.hrw.org/news/2021/03/02/uk-supreme-court-has-failed-shamima-begum