Will shakes his head at her declaration- not that she isn't hot, but Will doesn't think that's all that's going on with Malcolm. But he really doesn't want to get into why Malcolm's looking her way so intensely, at the expense of all others. So he leaves it at that.

"Yeah, I'm hoping I can do everything I'd like to, in there. I- uh- apologize in advance for the gruesomeness. Not that you can't handle it. More that serial killers always go the extra mile when they want to show off their handiwork." He rolls his eyes, but there's certainly an aspect of it he loves.