The Eternal City
For ancient Rome, sexual activity of any kind was seen as the healthy action of a good moral Roman. What was of greater significance for Romans was that of dominance. It was very important especially for Roman males to be in sexual positions of dominance. Having sex with other men wasn’t the issue but being a in position of subservience was. This was amplified if the person was of a lessor social position. If it was rumored or seen that a male Roman was acting as a bottom, or ‘serving’ another male or female that was seen as a sign of weakness and deficiency in moral character.
So in our story the rumor that the Emperor who is the highest position in the Empire was engaged as a ‘bottom’ for his servant and former slave was a HUGE scandal. The fact that they were both men was not an issue.
My source for this the extras on HBO Rome series in case anyone wonders.