Ren looked terrible. Obi-Wan knew that he wasn't sleeping well. This is the first time he's witnessed someone coming back from death and it certainly did not look pleasant. Perhaps talking about something would help ease the man's troubled mind if only for a little bit.

"Rey is staying with me for now. Your mother and Poe are also doing well."

He didn't know if he had yet talked to them, but that reassurance is there just the same.