He doesn't, but people keep thinking that because Ulysses is verbose, that means he's supposed to be right and a self insert. As if the script notes and placeholder text from the pre-release leaks don't make it clear that Ulysses is COPING AND SEETHING. Or you know, paying attention to the actual plot and dialogue.
In the dialogue files there's usually a joining descriptor of how the dialogue is meant to be said and the intent conveyed. Successful dialogue checks throughout the DLC are the player slowly getting Ulysses to admit he's wrong or stop being as dogmatic in his point of view.
The player basically succeeds.
I've bloviated on Ulysses before, but Ulysses
is coping because he's essentially in mourning. He's also seething at everyone and anyone he can hold responsible: NCR, Legion, Courier. Thing is nobody was ultimately to blame and that probably pisses him off the most. The final fight with the player in the scenario he wins was basically an elaborate suicide; he made sure Marked Men could flood the room right after so the Courier would die if he died, but what does that imply for him if he somehow succeeded?
The central theme through
all the DLCs involves some variation of "letting go" and moving on and Lonesome Road is basically the culmination of that. Only problem is you have to sit through
a lot of Ulysses.
Broad strokes, all the DLC's central characters are unable to let go of some piece of themselves or their past, for good or ill, usually with ego or stubbornness playing a part.
All the DLCs were planned in advance so there's a general theme linking them all. Every character is stuck or unable to let go of the past and that's what's binding them in some way, provoking some sort of action involving the player.
Graham -> Can't is let go of the role he once occupied with Caesar, Zion lets him execute righteous justice once more under a different banner. It's when you convince him to give mercy at the end can he "let go". It's also the only ending where he can move on whilst also achieving catharsis. His obsession is the result of guilt.
Think Tank -> Can't let go of their pre-war roles as scientists. Specifically, their role
as pre-war scientists, unable to acknowledge (and would refuse to even if they could) the state of the world outside Big MT. Mobius broke free of the role, but is similarly trapped by his friendship to them. He could've killed them all if he so desired but can't bring himself to. MT is also safety to Mobius, so he's willing to accept stagnation if it means security. Their obsessions are a result of pre-war roles and occupancy.
Elijah -> Can't let go of the Brotherhood's defeat at Helios-1. Defeating the NCR and the technology of the Sierra Madre would vindicate everything he did up to that point. His obsession is a result of ego and/or hate.
Ulysses -> Can't let go of The Divide's destruction. He tried to, only able to reconcile the lack of certain cause by blaming everyone he feasibly could – Courier (who delivered the package), NCR & Legion (former for expanding, latter for warring), the pre-war world (for building the nukes the detonated + plunging the world into its current state to begin with). and ED-E (for having the deadman's switch inside of him that prompted the detonation of the nukes to begin with). The Courier to Ulysses is like Salt-Upon-Wounds to Graham, basically. Not killing you basically represents them finally letting go of their past obsession. His obsession is the result of grief.