

He’s not a US citizen, he’s a permanent resident. Green cards can be removed if he has broken certain rules (mainly by commiting an aggrevated felony).
Its likely that in this case he hasn’t and could probably challenge this and win. But it also shows how green card holders are second class citizens as the goal posts can be changed and their protections under the law has limits.
And it also shows how Trump can weaponise the legal system. Even if this guy wins, at what personal cost will this be to him? The stress, the financial cost, the disruption to his education and personal life. Trump is using the apparatus of the state to punish individuals for political reasons.
Almost seems like Biden should have stepped aside much earlier so the dems could have had a proper democratic election for a successor.