What if you think of it as the PC telling party member 3 "hey, you're a dwarf, they're dwarves, maybe you should talk to them instead of me"? :p
Personally, I think the point of having a group of characters is that they all participate. Like, for example, when you encounter the lizard being assaulted in front of Fort Joy, you decide to keep your nose out of it, but your companion, The Red Prince, decides he's going to intervene anyway.
At the moment, it's like The Red Prince isn't even there.