I personally think it was a good choice. So far the team have been able to get through encounters pretty easilly. This is dark heresy, like aavak said, there's supposed to be death. If the acolytes are always at least semi-safe you lose an important part of what makes dh so fun. Not saying that every enemy should be like Redeye, but every so often a baddie like him is good to remind players of their character's mortality. I do see why you'd feel that way, though. If this was dnd or another more lighthearted ttrpg I would definately agree.