Just here to say this bug is still happening. Happened to me today.

Oh yes I know This one just surprised me since I purposely entered it solo to try it out first. Thanks for all your responses Now I know to just chalk it up to a bug

So I was playing the Directive 7 Flashpoint today in story mode solo, to try it out (had never played it before). I had just defeated the Interrogator boss and suddenly there is another player zipping around the area in their speeder! I've done quite a few solo FPs and I've never seen another player being able to enter my instance. I do question if it was some sort of bug. I tried to target the player to send them a tell and I couldn't. Anyone else seen something like this happen?

Plus I think a factor in why the protocol droids can't stack up to the other healing companions is that they can't equip a weapon or an off-hand item. So that's two pieces of equipment with stats that they miss out on. With those extra stats missing, their heals suffer.