"I think it's bad because it's torture," Strange responds, as if it's obvious. "Killing someone is one thing. But hurting them just because you can? That's barbaric."

It would have been easier for Strange to accept this had they just killed Ignatius. After all, if he had the opportunity and means to do so, Strange is fairly certain he'd at least make an attempt at killing Nightshade. But what they all did, forcing Ignatius to speak and then forcing him to relive others painful memories? Strange is a bit horrified at that.