i don't know about that.......
well first off, the opponent wouldn't warn him of it and there should be no outside help............. so they would have to discover that
next......... i don't know......... if that player fails to remove that gold berry, than they are broadcasting a fraudulant case....... by not removing the damage, the opponent might think that they have an advantage....... which seems kinda cheap to me........
i think that if that person doesn't realize it within 5 seconds of the next draw, then they are just outta luck......
it is kind of a surprise whenever you say "knock it out" and your opponent replies, "oops i forgot to take this damage off.... too bad you don't knock me out"
but that's just me, gimme a removal over healing anyday