OK, I know most FReepers hate lawyers, but as a lapsed lawyer, I gotta say, cases like this are why you need one. A good lawyer, doing his job, would have advised the family during the adoption that they had to pursue citizenship.
Now, it could be that a lawyer was involved in the adoption and didn't know enough to advise properly. Then shame on them (probably too late for a malpractice case now). They shouldn't be doing international adoptions.
If the adoption was done by the parents by just filing papers (since he's marrying the mother, I can see where there might be some streamlined, do it yourself adoption process for these cases), these results point out why you should at least have a lawyer go over the papers or have a consultation so that you know you are considering everything that needs to be considered.
The kids sounds like a loser, but I can't imagine being sent, permanently, to some country where I didn't know anyone, etc. If they think he's a criminal now, just send him overseas and watch what happens to him....
Unfortunately, there are hundreds of young people exiled to countries they don't know under just these circumstances. At least in the Phillipines people speak English. Imagine being sent "back" to Korea or Thailand or Russia.