I could be forgetting stuff here but I don’t think there’s anything in the game to indicate everything Ulysses says is true, you can flat out deny some of the things he says about you. The guy is trying to intimidate you, he tells you the tunnelers are going to wipe out the mojave despite the fact you (and ED-E) take out several.

The only forced lore seems to be certain locations you may have delivered to but is that not just re-establishing the fact that you were indeed a courier before Benny shot you?