He doesn't really understand that the singing is powered by dynamis, because how could he possibly, but he does react with surprise about the offer to do so now, nevertheless.

"I'm not entirely sure I have a good song in me right now, honestly. Maybe after I sleep for a million years. All of this has been barely even a day and a half for me, and I haven't slept since I got back," practicalities first, for all he pushes himself, but then he does add, "If you want to help me get cleaned up and then sing me to sleep, though, I'm not going to complain."

He does the thing where he clearly means a bath and to sleep and also very clearly is including sex in there somewhere.