It's plausible. It's implied that the strike team + Revan can't beat Vitiate, so the gap between Revan and the Sith Emperor is probably at least comparable to the gap between, say, RotJ Vader and TPM Sidious (this isn't a rigorous fact and as with all of these ideas, involves some leaps of faith, but it seems plausible). [Legends] canon tells us that TPM Sidious > Vitiate.
How big is the gap between Vader and Maul? Maul is modestly below Dooku, but not unimaginably so. Dooku is probably fairly substantially below Vader as a Force user, but I think it's plausible to say that the gap is smaller than the Vader-Sidious one given that Vader does struggle with Jedi that are probably not on Dooku's level albeit before his prime in RotJ, and seeing as how Yoda only absorbs Dooku's lightning "far from easily". So let's say the gap from Maul to TPM Palpatine is like twice the gap from Vader to Palpatine, and ergo from Revan to Vitiate.
What's the gap between Luke and TPM Palpatine? Is it as big as the gap from Maul to Vader? That's plausible if we're talking about a no-holds-barred prime Luke. He's stated to have inherited his father's 200% of Sidious's potential. By DE, he just needs some "hidden resources" from Leia to beat DE Sidious, potential that can probably be unlocked with 30+ years of growth. He should be substantially beyond TPM Palpatine. I don't see how one could look at Luke's growth curve and, even knowing that he'll probably hit diminishing returns, conclude that in 30 years he can't make up the ground, if any, between his DE self and TPM Palpatine, and then enough to cover the gap between Maul and Vader.
I'm tired and rambling so this may be a little weird.