Then what does it mean when those who speak of Ulfric going to Sovngarde also support the Colovian? Also claiming he is not honorable? Does this not contradict one's argument?
Not necessarily, because though he may have fought what many see to be wrongheadedly, he did fight bravely and with conviction. It's no different to me than when some Stormcloak Nords say that their Legionnaire counterparts lack honor (and by implication have no business in Sovngarde). Yet, Rikke finds her way there. Remember that even Torygg is present in Sovngarde, as much as some people like to try to tear him down and cast him as an unacceptable weakling who couldn't fight his way out of a paper bag. He was not perfect, but he faced his fate honorably. As someone mentioned earlier, is it possibly more about the manner of death, rather how one faces it, than the (mis)deeds of life? I'd have to do more research into the lore of Nordic custom to know for sure.. Not to say, of course, that a merciless Nord brigand would get rights to the Hall in Sovngarde because he faced death without emotion. I think there's more to it than that. And maybe it's not even all quantifiable, or able to be qualified.
We should also remember that Ulfric is not swaggering and blustering when we meet him in the afterlife, it's quite the contrary. While not fully repentant for his actions and his overall cause, he readily admits the tragedy of it all, how it served to fuel the World-Eater and how his people were "betrayed" and thrust into such bloody chaos. He was a warrior to the end, though. I do believe one can simultaneously harbor ambition and altruistic desires (most especially where it concerns those one considers kinsmen). And really, even
if Ulfric was honestly devoid of any and all hopes of the crown or personal glory, and was blindly convinced that his actions were just, we can still disagree with his assessment and oppose him. That doesn't change the fact that he was a fighter to be reckoned with.
To me, it's no different than Ralof and Hadvar expecting to see each other in Sovngarde at death. They're on different sides, but the honor in fighting with courage and standing your ground seems to be broadly acknowledged by the Nords. In that way, I don't think it's necessarily incomparable to the men fighting on opposing sides in the US Civil War. There was, according to several sources, respect shown during and at the end of the war, owing in part to mutual acceptance of defense of one's home and livelihood. They were all kinsmen after all. And therein lied the great tragedy.