Also, the connotations of violence in the raised fist make it a bit too blatant for an organisation like the Hegemony to adopt, it'd seem to me. You'd have to have a pretty damn bad lack of PR sense to create an organisation with the aim of bringing the Sector together as one entity and then give its symbol that adversarial a tone.
In that light, I'd expect the symbol to be something that evokes thoughts of space (as a thing that the Hegemony helps gulf for the members), protection (say, a shield) or some generally positive symbol of authority/nobility of spirit (swords, eagles, maybe stars, that kind of thing).
That's my 2 centi-credits, at least.