Based on the fact that you clearly think you can easily beat me in a fist fight, do you really believe that I could have found a way to kidnap you?

[ The answer, of course, is yes, Sherlock could absolutely figure out a way to kidnap a person, but that's besides the point. He's aware that physically he doesn't appear to pose much threat, so he hopes the man will just follow that line of logic. ]

At least now you seem concerned with the right thing. It seems like we were all kidnapped, myself included.