This time is a little bit an emergency. [He says it in tone as if he's agreeing or conceding to Sans's boundary, but he isn't. The real agreement is to his rephrasing - just in an emergency, life or death. He's not accepting a closed door on future incidents like this, not if he's in perfectly good condition while Sans is literally dusting out in front of him.

His hands tremble as he works, and he locks it down again with carefully automated movements. That bone, and that bone, and... the smallest one he's tried to move yet, it crumbles under his fingers. He knows it's not from excessive pressure, he knows he's being gentle...

Which means this is as good as they're going to get, as much help as he can be without healing magic of his own. He flings a few more frustrated messages the tracker's way, because the lost minutes could have made a difference, before he forces himself to push it out of mind. What he can do now, what they can do now, that's what matters.]

Okay. Just think of it as me healing you, the way you've healed me! It's fine. It's fair. [His jaw trembles as he adds:] I would do it, i-if I could.