It will be interesting to see where Newcastle are in relation to Milan on this, looks like they sold a player they knew was heading for trouble.
It'll be interesting to see how that goes, but I would suspect that there's very little to nothing they could do. Had he been charged at that point? No.
Had he been found guilty of a crime? No. Is there any legal responsibility to disclose any unfound suspicion, which is basically conjecture? Nope.
If you buy a car and you know the engine is still working but is on its way out, are you obliged to tell the buyer? No, but morally it's a bit meh.
If this is an additional charge, which is what it appears to be, then it's the FA suspecting he has put bets on here while under our jurisdiction, so another ban.