Caustic and Gibraltar without shield don't get downed by Arc Star

With the Season 2 patch, Arc stars were both nerfed and buffed. The buff was in regards to sticking a player without shields and downing them. This means that a 100% health player without shields would die if he got stuck with an arc star (wraith going into void excluded). I've noticed however that sticking an arc star on the bigger boys does not down them which seems like a bug to me since this wasn't mentioned in the release notes.

What I think is happening is that the Arc star deals 100 base damage when it detects someone doesn't have shield, but doesn't take into account the 15% fortified buff our bigger guys have. Please address this issue because it's really annoying early game to think that you've downed someone, just to look back and see they're still up and you still don't have anything to shoot them with.