He's not that easy to stun and while you save him for last he can punish you
I keep thinking that will happen, but it never does. He's super slow and at most gets one hit in before he's toast, and that's if he doesn't get stunned first. If I had to choose between Opress as the last guy standing or Fives, give me Opress any day (and I don't even think Fives is all that great.)