I understand he's just covering his ass but the fact he has to say it tells me that the possibility no matter how small will be there.
Getting annoying here with the questions but is there some kind of clause/guarantee that a doctor agrees to that if it comes back he'll re do the op?
Questions are not annoying at all, they are very good questions bro

Answer-
No and that's why he says it may come back, because if it does then he is not responsible. So no clause or guarantee, that is why you have to go with the best of the best, the one with the beast rep.
This guy has done over 2000 breast implants and has removed gyno a lot of times in the hundreds, he is the best. Oh btw, he says out of all the people he has done, not one has been back or reported the gyno coming back. I still think the possibility is there but unlikely.