The real reason you don't see them is because academia used to think they were too obscene or prurient to display, but the reality is that sexual depictions on red-figure pottery are common. This sort of academic paternalism is also why a lot of the sexual terminology in the scholarship is in French: this was seen as a way of ensuring that only sufficiently educated people could understand the references, as though this would ensure their interest was not prurient.
While the sexes are correct, I would be a little hesitant to interpret this as signifying widespread acceptance of homosexuality between men (at least any more than heterosexual sexual graffiti indicates widespread acceptance of promiscuity). The sort of homosexuality encouraged in ancient Greece was one we would find repugnant today: sexual relations between older men and younger boys, as some sort of weird mentorship with sex as the payoff for the mentors. Sexual relationships were seen as involving a dominant and a submissive partner, and it would be pretty taboo for an adult male to take on the submissive role (though it might be a badge of honor for another male to say he was so dominant he was able to make another man submit to him).