By this time, though, he's much more socially adept than he pretends to be . I don't want to repeat too much what I said in another thread, but this wasn't in response to something off-the-cuff. He'd put a lot of thought, research and planning into that speech, and he's very good at manipulating people. Of course it was supposed to be moving. (That doesn't mean it's insincere).
I find it hard to accept that he's suddenly clueless (even if that's what was intended, I can't go for it). If it's just to give us "cute" Sherlock, then I think I can leave it out of my personal picture of him .
I keep thinking about how well he holds it together in TRF, keeping control of the situation, even knowing what he's got to do and what he's got to give up. I know TSOT has to take us through to HLV, where he's almost a dumbed down version of himself in some ways (not all), and he never gains control, never mind keeping it. But in HLV he still has his manipulative skills, and he's not "a child" at all.