Why doesn't he just fly to El Salvador directly and save time. I'm a Caucasian male and I wouldn't go to the US right now, he definitely shouldn't risk it.

I'd be problematic anyway because I genuinely don't have a social media presence, which I'm sure they would find suspicious. And I'm pretty sure my 70-year-old parents don't have one either.

Your friend needs to ask the people who paid for the tickets if they'll pay for legal representation and to get him released from whatever incarceration awaits him if he falls foul of the regime there. Assume this could run to hundreds of thousands of US dollars.

Also, given your description of him, I think that's incredibly likely to happen.

They'll say he's guilty of something, so those friends won't be sure whether he acted illegally or not.