Despite the lack of respect, Shima seems cheerful, dispelling whatever he did just as quickly as it happened. Strange is on the right track, and Shima can't help being a little smug that in a round about way he's actually saying that Shima is "more capable". Also, the more Strange starts to talk about how right his own opinions are, the more right he starts to feel. Probably a very familiar thing for him to feel, honestly.

"Haha, well maybe it's harder ta hit stuff with an illusion?"