Not sure if intentional but that's pretty much it. I never tried bumping them before but it's important as a gunner to keep things away from you, so I tried with swiftstrike, the go-to shield of gunners, and it wasn't working so I assumed they couldn't be bumped. But then a teammate started bumping with his Crest of Almire. Why can't swiftstrike bump trojans? Is it because it's 3* and I was in FSC?
Shield stats affect your ability to shieldbump enemies. The stronger enemy, the better (more health) your shield has to have.