I don't think ITC can economically bully people, they likely can ransom peeps if they are literally giants but they can't really bully them when they can just say "nah" and they could still operate reasonably with the wealth of resources they already have. Then again, not necessarily all colonies are developed enough they can do decent exploitation of their own system. Some colonists might be brand new, even. They might explicitly need the ITC economic aid to just survive. That'd be a curious development.

Anyways, I think I could drop the space nomad thing. Alternatively they could had O'Niel space colonies in the past but the gates explicitly forced them to change that. Now I am only have to imagine up a plausible shape for said colonies. Perhaps the same cylindrical setup but with multiple layers with each providing gravity through "gravity plates" tech?