This was a finding by the immigration judge, was appealed to the relevant court, and that determination was upheld.
The process that is due to an illegal alien was given to him, and appropriate to the context.
There is a miscommunication here.
To me, it seems you (and others) are saying that there was a process where the core issue was "is he MS-13?" and it was determined he was. In other words, was he ever charged and convicted as a member of a gang? I believe that is what the insane filing was talking about when they said "without the semblance of due process".
The filing you reference (added on the 31st, not the 24th) is the initial sentence for the issue related to immigration, and the appeal for that decision. (Initial
decision,
appeal). The information about him being MS-13 was considered to be reliable and informed the choice, but it was one of the factors.


You will notice here the "Respondent has failed to present evidence to rebut that assertion".
For the thousand time, I am not a lawyer, but I don't think that is how a process to determine if he is in a gang would be framed as him not being able to prove that is not a gangbanger.
The judge does say the membership is "verified", so I am happy to go with the assertion that a court considered him MS-13. But I can still see that this is for the purpose of immigration, it is not a court to determine if he was a gangbanger or not - again, that is what they meant by "due process".
Anyway, the appeal judge uses even less strong language on how certain is the gang affiliation.
Fundamentally, it did not matter whether he was or not, just the risk that he was a gangbanger meant that he was too much of a risk. All other evidence (never claiming asylum, etc) pointed to him not being a good candidate for staying indefinitely in the US, thus the decision.

I think this push of making him "for sure MS-13" is risky for the government. I think they should be more cautious in their word choice. For an internet forum, go ahead, idc. As a legal point, I don't think it is that surprising that an activist (judge) would point out that he was never given due process in regard to his gang affiliation