That is your definition of GOAT. Mine is that there can only be 1 GOAT, and you earn that by being the greatest of all time. Not in a couple of years, just from the beginning of time to now. Pogacar is currently having an amazing season, and is still not close to the best seasons of Merckx. If he indeed wins the TDF and WC, and Lombardia, one could say it's one of the best seasons ever. But that's a bit premature.Again: when anyone (like me) calls Pogacar a GOAT it doesn't mean he is actually the GOAT, but a statement about 1) his potential as given by his current palmares to 2) actually be the GOAT in the near future. You can attribute the GOAT status to anyone rider but if his palmares doesn't back it, your belief is not well grounded.
So of course "Pogacar is the GOAT" is a statement about future prospects that can thus prove to be false, either because:
1) he's not actually GOAT material
2) because someone better came along
3) he will have an accident
4) he will be unlucky
5 he will begin to fade.