Hmm, my idea doesn’t work. Because “I hold the rival’s trade agreement, and can do a thing with their permission” is an exception to the general rule of “I have the only ships in the system”. So if Fed arrived and returned the TA, they’d fall foul of that general rule and still not be able to Hegemonise.
I’ll add back a Fed Culture.
I’ll move this over to Discussion after I’ve posted it.