Has there been a recent monastic ruling amongst Dharmaguptaka monks in China & Hong Kong with regards to a policy of denying ordination to laymen who have lived homosexual lifestyles prior to cultivating the aspiration to go forth?
I know that it is quite clear in theravada vinaya that homosexual men (not the same thing as straight men with homosexual experience) to ordain into sangha. If the sexual identity of such person is discovered after ordanation, he must be dismissed from the order. Compare to some other conditions whom the vinaya would not allow to ordain . if the teacher accidentally doing so without knowledge and later discover it, he would allow to stay in the order. (I can't remember for sure what conditions, it might have been those with certain diseases).
Anyway, as a Buddhist, I believe Buddha did everything out of kindness to all of us. He would not block anyone's path to liberation. Tho he didn't say so, but maybe it is better for gay men to reach path of enlightenment when they are not staying with a group of men?
Among the lists of inopportune beings who would not reach enlightenment in current life time, sexual orientation is not one of them (tho it might appear in later commentary, there was no record of Buddha himself saying that).
All and all, there is no record why Buudha did not allow gay men to ordain into Sangha, but whatever reasons were, I believe Buddha did so, like all things , out of kindness for all us .