Sherlock is prickly and hard to get along with, but he truly hates it when people or creatures are exploited, especially when they're physically harmed.

"I will, but you can thank him yourself the next time you come to the brownstone, if you like." Sherlock is still wary of Ted, the same way he's wary of anyone who gets close to Joan, but even he has begun to grudgingly accept that Ted's friendliness and optimism are not subterfuge nor stupidity, and that Joan is truly happy with him in a way that she has not been happy in a long time.