If I were him, I would plead no contest, time served, I'll go to Costa Rica.
Unfortunately, I think they can deport him. They can deport people for misdemeanors etc. (I think it's at the whim of the president) I had a relative deported for, "Likely to be a charge". My grandmother was deported because she had an eye infection.
Abrego's status was that he had a removal order, but couldn't be deported to El Salvador.
Abrego Garcia also applied for "withholding of removal" status.[63] This request was granted by immigration judge David M. Jones, who issued a removal order but barred deportation to El Salvador,
So, at this point in 2019, he can't go back to El Salvador and ICE decided not to deport him to a third country, because yeah, it certainly wasn't worth the hassle. They allow him to stay here, work permit etc etc. However, all that stuff is subjective. He can still be deported to third country because he has a removal order, but was allowed to stay. See how subjective this is. These days they are deporting people for just about anything....Along comes Trump and his El Salvador prison BS. Abrego is sent there because they aren't doing due diligence. .Because it never occurred to them that there was an actual order out there or they didn't give a shit. Who knows how many they sent to that prison who had orders, but they didn't speak up?? And Trump's standoff against a court order and that awful prison etc etc etc....
Anyway, if I were him, I would just want to go to Costa Rica and
get out of this shithole