I think it is indeed immature behaviour, which I must applaud. It most certainly wasn't sexual harassment behaviour. She didn't mention who the celebrity was, but I can imagine a comedian or someone doing such a thing in a private attempt to get a reaction on live tv - it was a cartoon willy sketch, not "here is a sketch of what my penis looks like, what do you think of it".
To call this sexual harassment dilutes the seriousness of real examples of it.