No, murder isn't sociopathic--forcing Charles into the process as participant and victim, however, is a real problem and not just in boundary lines but in the means versus ends and where you draw the line. I kill someone for killing a family member is one thing, but requiring my BFF to hold them still while I do and experience it is something else entirely.

He held Shaw in place even when it was completely obvious what was going to happen, followed it through to the end despite the personal cost (physical/psychic, philosophical). And I'm still puzzling through why he did that. He didn't have to drop control of Shaw to save his life, even if it ended up being only temporarily.

Before Erik went whee-helmet, Charles, under obvious strain, said he couldn't hold a man like Shaw long; they were on a timeline to do whatever they were doing (I will argue what in the name of God was supposed to be the plan there, though). I'm thinking from what they showed--and from the fact Charles was under obvious strain and no one really wants to live through being lobotomized before death--he couldn't risk dividing his attention from Shaw and risking Erik dies by nuke. Once the execution started literally, he couldn't let go and was trapped in Shaw's death.

I will admit, there's a fair to good chance that purely by observation of Charles using other people's senses and controlling their bodies, there's no way he could have predicted Charles would live that death.

That part was a choice; he valued Erik's life over Shaw's--but I dont' think, from the way the movie set it, that there were many more options than hold or let go entirely.