Thanks to @EnjoyTheJourney I was able to test Cimerora with that no-cap build.
In summary, they are much, much harder than Trapdoor mission. Cimerora isn't part of the game I've ever explored, so I didn't have much idea of what they did. I died a lot at the beginning. Eventually I figured out how to attack their groups though and started killing them without danger. So, on a character I played less than 2 hours against a faction I'd never seen, I was able to take that no-cap build into no danger territory.
I imagine anyone who put some time into their character would blow me out of the water on that.
I'm not sure I could have the same consistency with a Blaster actually. So I've finally found what Sentinels do. Thread objective achieved.
Sentinels are Blasters who can solo much more difficult things, but still not the most difficult things. That's a pretty small niche, but I guess it's a niche.