To be angry and disgusted at it would be incredibly hypocritical. Consuming humans is a necessity to Ken, consuming Ghouls became a substitute of that necessity that eventually grew into something a lot more fucked up. He has no right to show contempt at Will for what happened, and from the information will gave him, the man didn't even know what he was eating and didn't really have much of a choice (a serial killer, right?).

He waits for the answer as he takes a sip of his coffee, watching Will. There is no judgement; he can't judge. The last person allowed to judge anyone is Kaneki - he can't judge, he can only be judged. He can't talk to others either; his best friend is terrified and possibly disgusted of him so Kaneki has to pretend his best to be a normal human in front of him (and normal humans don't eat people and ghouls), another of his best friends is a ghoul and Kaneki has hurt her too much already, Annie has her complicated life to deal with under the government's thumb, Reiner and him had a fall out after Kaneki tried to eat his leg, Nishi is completely insane and not a friend, and Kaneki has perfect other excuses for not to talk about it with other people.

He would have one for Will, as well, but after those two months of talking to the man and now this... well. yeah. In the end, Will is going to be the only person Kaneki will dare to talk about any of it, probably.

"I don't think you should be guilty of it. It happened, you couldn't have stopped it." Kaneki doesn't care about callousness. He used to feel guilty, he used to cry every single time he put a bit of human flesh into his mouth. Look where he is now, stealing bodies with Touka, cutting them with his own bare hands.

"What changes have you made?" what sort of view does he have now?