Look, here's what we know.
No Stand or ability in JoJo can get one up against RTZ.
GER failed to react to Diavolo in time within the Epitaph vision, even if he's still hilariously fast.
GER was effected by time erase, initially, but RTZ wasn't, and GER only regained control after RTZ kicked in, allegedly.
GER's stats upscale him above every Stand, including the Infinite ones.
We know, from direct confirmation, that in some cases, a stat can refer to an ability itself, not the Stand, even if some stats do indeed refer to the Stand itself, even if other stats do indeed refer to the Stand itself within the same list.
Such as with Whitesnake.
So put simply.
We know something about GER scales to Infinite.
We know GER itself isn't infinite based on Epitaph.
We know that the thing that says something is infinite could also be about an aspect of an ability, not the Stand.
And we know know nothing can get one over RTZ and that RTZ could act when GER couldn't, allegedly.
That info suggest that RTZ is simply above GER and is the thing scaling to infinite because GER itself can't.
From when letting a character hitting you when you wanted to just use your ability is an "anti-feat"? GER, as you said, wanted to **** with Diavolo, so it wasn't serious at start, and it blitzing Diavolo 2 times confirms that it was casual af in the Time Skip.
Yeah, he wanted to **** with Diavolo, but GER kinda doesn't have any say on what a guaranteed future shown by Epitaph is, Efi brought that up awhile ago actually, GER may have wanted to **** with Diavolo, but he didn't control or have a say in Diavolo being shown him ripping out Giorno's heart, that was fate itself showing it and I doubt GER would have just let Diavolo gouge out Giorno to **** with him, given he kinda actively didnt allow that future to come to pass.
He can blitz someone beyond belief, that doesn't warrant an infinite rating by itself though, and the stats
would actually imply infinite in conjunction with that, but due to the anti-feat, the best we can say is that GER is just ludicrously above him, not infinite and given we know sometimes a particular stat or few in a sheet can be about the ability instead, and we have direct confirmation by Araki that can even be the speed of the ability, that's what we're lead to believe, that RTZ is what's infinite.
Though, if you want to convince Efi that the Epitaph anti-feat doesnt hold weight, go ahead, because I'm gonna be honest, I don't particularly disagree with you, but this is an actual issue in play here.