I still have to say after a blow like that to the head, it doesn't matter how committed you are to the cause of bringing Ripley home, you just don't walk around as unaffected by it as Bishop is. I'm open to the idea that he's not an android, I don't overly care on a personal level what he is, but if so, the fact he can practically ignore that injury and do what he does and say what he says, has got to be some very bad acting combined with bad directing and research, possibly writing as well, which allowed for the complete lack of realism.
While human ears are easier than you might think to tear off, a blow to the head with a solid metal pipe that tears off not only the ear but as big of a chunk of flesh from the skull that's shown in the movie, that's just nothing you get back up from like nothing happened. I know people take more abuse in movies in general than what is normally humanly possible, but that scene is just a bit over the top, imho
I really think Bishops clearity and cold focus even after the blow, was intentionally directed and acted out that way to show that he was after all an Android, also adding just another situation where it proves you cannot trust these corporations.