] Part of me sees Henry probing for CM's opinion of the buffoon before them, (i.e. how will this perfectly sweet girl describe something distasteful), while another part of me sees Henry trying to change the subject and remove JT from Catherine's mind, (providing her with a more enjoyable subject, like himself.)

I would say that perhaps even he is jealous of her attention. I also do not think that he is in love with her yet, but that he wants her to fix his attention on his wit. It has often been said that Henry valued Catherine because (among other reasons, of course) she was a willing audience for his conversation. JT was taking away from Henry's stage time.