Strictly speaking we dont know, if he is a winning player, since everyone can win money in freerolls. It does sounds weird to me though, that someone would have $800 in their account and not even have tried any regular games? Its certainly not a normal playing profile, so something about this whole story seem wrong to me
If he opened the 888 Poker account not using his real name, I guess, it could also be an option to just forget all about that account and the $800 sitting in it and then open another account on 888 Poker this time using his real name and other credentials. And then of course not tell 888 Poker anything about it being him, who was the owner of that other account.
Like maybe he opened the old account, when he was 16 years old, but now he is of legal age and can open an account in a regular way. For this to work he would probably need to change his internet provider and the gadget, he is playing from, so that there is no obvious connection between the two accounts.
I am generally not recommending people to break the TOS of poker sites. But in this situation the breach apparently happened already, and if he opened a new account, it would not hurt other players or 888 Poker, and then the lost $800 will hopefully have tought him the lesson, he needed to learn. If he already came clean with 888 Poker, then this obviously wont work.
I have no experience with Party Poker or GG Poker, but in my opinion ACR Poker might even have a tougher player pool than PokerStars. But of course it depends on, which exact games you are going to play. SnGs on ACR Poker are fairly soft until $3 games, but already $6 games are very reg infested.