The not-hug is fine. Mettaton doesn't think he's ready for a hug, not really. The distance is nice; it implies a sort of quiet respect that he hasn't gotten since the break up. It's... refreshing.

Honestly, it's not a question of whether or not he's going to forgive Sans. Of course he does. Well. Maybe not right now, but he will. He understands where the anger came from, as much as Mettaton did enjoy playing the victim and pretending otherwise. The question is whether he'll ever trust him the same way again.

...that answer isn't looking so good.

At the very least, the robot shakes his head and scoffs lightly. "Can I worry about my charge port?" His voice is still crackling and strained, but at least it's a change of subject.