Let me add that the biggest insult to Caesar's "dignitas" here, is not that he had sex with a man but that he was the one to be sodomized.... In other words it was not primarily the homosexual act that was used as an attack on Caesar but the fact that he took "the woman's part." If it had been Nicomedes who had been in the "receiving" position then the insult would not have had as much sting. It was the idea that (as Suetonius put it) that "Caesar may have conquered Gaul but Nicomedes conquered Caesar..." that was the insult.
This gives some insight into the patriarchal culture of ancient Rome. Over and over again -- in the poetry of Catullus, in Roman songs, in graffiti, in comedies -- it is made clear that the homosexual act itself was not frowned upon (at least not as much as the Christers would frown upon it) as the position of subservience during sex. If a soldier in the course of raping and pillaging a conquered town forces a young boy to suck his cock, all well and good, but if that same soldier voluntarily sucks another man's (or boy's) cock then the gossips of ancient Rome would condemn him and seek to shame him.
There is a moral parable in imperial and patriarchal hypocrisy here somewhere.
Jerry