Deja motherfucking vu... Good to read your scripture as always Sloppy. It seems you overlooked the role of women in all this, though. Although they are not the sculptors of socio-sexual spheres, they are often the forces that induct future generations into these sphere via their (stereotypical) charge of the domestic sphere.
Culture is of the vultures anyways.
That said... addressing the main discussion (if I understand correctly):
It seems you're referencing the lack of homosocial (erotic undertones definition) counterparts to heterosocial (if I may defy spellcheck for a moment) bonds in media targeted at children too young for sexual understanding.
While I do not believe depicting homosocial relations is inextricable from depicting overtly homoerotic relationships (ex. Sherlock and Watson in the recent remake), I think it's a little more complicated than that.
Until further work is done, it would seem the majority of people lean towards heterosexuality. This means, according to psychosexual theory, they are more predisposed to understand heterosexual relations via their parental and environmental exemplars and their own pregenital psychic urgings (oral, anal, and, most importantly, phallic). There's less need to give them "the talk" to illustrate the difference between a boy's "girl-friend" and "girlfriend". Without the prerequisite implicit knowledge of homosexuality presented within their environment and in themselves, parents may feel they need to give "the talk" more prematurely than they would like to instill this knowledge and understanding in their kids. Let's not forget the abundance of sexual stereotypes and niches of the community they may need to address in this discussion. With younger kids, parent may not want to have any "talks", let alone a talk like that.
For another example of how this prerequisite sexual knowledge may be a hindrance to introducing marginalized communities to younger children (RUN ON^INFINITE POWER!! sorry), the concept of teen mothers and virgins may be useful.
While being a teen mother in and of itself is sexual, there are many elements to the demographic characteristics, stereotypes, and stigma, that are not. For starters there's higher drop out rates (easily explainable to a younger audience), lower income and parental abilities, higher rates of substance abuse etc. However, teen mothers are not often depicted to younger audiences, when even bad mothers (ex: Evil Step-mothers) could've become a Disney staple. (Not that all teen mothers are bad, just saying that element of teen motherhood is not taboo in PG media) This may be because some more nuanced understanding of sexuality may be inherent in grasping premature motherhood.
This rhetoric seems applicable to discrimination (to say the least) against virgins in many Middle Eastern (not all) cultures as well.
While I think there are homophobic hands well at work in censoring the media, I think there's also an effort to streamline things for parental comfort. I think as less graphic and sexual stigmata are placed on the homosexual demographic; I think parents should be given more of a responsibility in addressing sexuality discrimination.
Wow, I bet I sound like pompous Ph.D toting asshole. Sorry...
*Backs away from the thread*