No, there is no option for Wrathion to rest. He'll rest later. When they both can. Mostly, he's concerned that Anduin will run out of steam and end up somewhere in Godsblood without the wherewithal to get back to the boarding house. Wrathion doubts that he'll do something to make things worse with his leg, so long as he's not forced to balance on the bad one. He finds that unlikely.

"If I was going to do more damage, I've probably already done it." But the dragon shrugs. He could go into detail, but he honestly isn't out to make Anduin feel guilty for the choices that Wrathion had made. Of course, in his casually arrogant way, he's also sure he'll be fine, given time.

Wrathion has absolutely no idea as to the direction in which Anduin's thoughts have turned, or he would have something to say about it. Assuming, of course, that didn't drive him into a bellowing rage, first.