Dude challenged Delenn (AGAIN!), thought he was bad ass while runnin' away from Lennier, tried to kill Marcus, and then interrupted the ceremony to tell Delenn what she already knew?
He's a dick.
Ran away from Lennier? When?
And wait until you hear Delenn's assessment in S4. But even so, his revelation, painful as it was for Marcus, changed him. He's not necessarily the most likable sort, but by the end of the episodes he's no more of a dick.
Consider the situation from his POV:
"A religious zealot, propelled by prophecy into a position of military and political power ... always a bad idea."
It's true he went off kilter in his followup to that view by threatening one of Minbari society's most sacred of laws. Yet there is much more to come in S4 to add to the overall assessment. Then again, that doesn't help with where things are at this moment.