LOLOLOOOOOOOL.
PoD Bane is already a faster-than-eye-can-see fighter, while we see Thanaton in cutscenes and he clearly can't compete with that, so he gets blitzed. Also PoD Bane > Kas'im > Tulak Hord who can take down a capital ship, which Yoda who struggles to lift pillars can't, but Yoda = RotS Sidious who can't be monumentously weaker than RotJ Sidious, who is a universe buster given that he can use Force storms but can't control them. Bane is a universe buster, he wins obviously.
I don't see Bane's Forcs defenses protecting him from Thanaton's lightning, and I personally doubt Bane'd have a defense against Thanaton's sorcery, given that Revan himself wasn't proficient in sorcery, nor do I think he'd have much knowledge of it after only spending days on Dromund Kaas and facing Vitiate once. Granted he glimpsed into Vitiates mind momentarily, but IIRC he and Malak actually convinced themselves that they chose to become Sith and thus, with their minds already messed up from meeting Vitiate, didn't remember much of anything from their time on DK. Also, reflecting on the game, the only sorceries that Revan possessed was Drain and Death Field. Comparatively, Thanaton has a far vaster array of powers and sorceries, not to mention defenses. I don't see Bane pulling many, if any, wins against Thanaton.