[Nope. He does not trust that hand! He's getting dizzy, and he thinks that yes, it probably is for the best if he killed Shirou. He probably can't do it right now, but he certainly doesn't want to let him get close again. He doesn't want anymore pain today. He doesn't want any more awkward forced masochism, either. He's had enough, and he can't trust Shirou to be kind. Even if he was nice now, just being touced and moved around by someone else is going to hurt and set off that objective. So the thought of Shirou getting back in his space is enough to cause a gut-deep fear that overrides proper thought.

Shirou can have his knife back. In his hand.]

Get away from me.