Sorta. The idea is that Dragonborn is either a Shezzarine, for either having Shezzar's soul, or by mantling Shezzar by aligning himself with Shezzar's interests (protecting the Mundus from the dragons and the Thalmor). Tulius and Ulfric and Dragonborn scream the same trichotomy as with Hjalti/Tiber and Wulfharth and Zurin, which is where that theory comes from....I think.
Tullius + Ulfric Stormcloak = Talos Stormcrown... + you. Add in the Rebel/King dynamic, plus you taking on Shor's role in fighting Alduin.
It could be a case of Enantiomorph-ing, or it could not. If it's not... that is really one hell of a coincidence.
I don't think I'd want the Dragonborn to be a Shezarrine. Pelinal Whitestrake and King Wulfharth seem like insane [censored]s, and Shor himself is described as a bloodthirsty warlord.
And Nerevar was a devoted Padomaic. Cyrus is often a greedy [censored]. Don't get me started on Vivec.
As Dargor implied, if a bit of protagonist sociopathy here and there disturbs you, you may be in the wrong game universe
.
They all did really good things too, however, just like Pelinal and the rest. TES nuance/greyness is why many of us are here.