As I recall, the difference would be that the senator actually did proposition another guy in a public toilet, which is a crime against "public decency" in every state, I would imagine.
But the other guy talking about young girls was - according to the law - talking about crimes but not yet committing them. That's not a punishable offense in law, I think, until the guy actually begins to plot with others in a way that involves real plans and real victims. That is, if I fume on the net about how certain kinds of people ought to be killed, that's not against the law. But if I actually conspire with other people to go out and kill others, then I have broken the law.
I think what this shows is that law always lags behind where society stands on any given issue. The legal problems posed by the Internet are only not being met with effective workable legislation, which is incredibly difficult to formulate and execute, and even more difficult to enforce.
Nobody living can ever stop me
As I go walking my freedom highway.
Nobody living can make me turn back:
This land was made for you and me. (Woody Guthrie)