Is it, or would it be a bug though?
I'm not saying it is or isn't but constantly summoning the infernal might displease others in the group. I'd parallel it to playing a Necro that always summons the dead, eventually the "good" people in the party will just walk away, if not outright end the evil practice. There will of course be those that would also accept the practice and stick around; it's just finding those people/companions. (unfinished game being unfinished in mind)