Isn't it ironic that Henry calls the very social graces he is trying to teach his pupil "tomfoolery." I suppose he means all the things he finds ridiculous. Let's see, that means being polite, speaking about things everyone can relate to, using good manners...all the things he could care less about doing. Those are valid and appropriate behaviors to be used in social settings.
On the other hand, there are some components of this kind of social interaction which are quite ridiculous. How about the fact that one must only talk about surface matters, or that one may only make a social call at prescribed times, or that certain ways of sitting, sipping, eating are required to be socially acceptable.
Pygmalionis a commentary on the role of social class and language. "Tomfoolery" would most definitely be a socially unacceptable term.