Straight people often (don’t) have children. Assuming that it must be this or that, forever, is absurd.
It’s about the expectations about the likelihood of having descendants that the knowledge that the man was gay create in everybody else, especially was this was quite some time ago.
(People naturally assume that gay men are far less likely to have children than straight men, for obvious reasons which I assume I do not need to explain to you)
Such expectations then fed into expectations about the future of the DC Universe.
All this makes the discovery that people were wrong in their expectations a pivotal and thus key element in the whole story.
I’ll make it easier for you: imagine that the man was a catolic priest rather than gay, and then imagine that the story teller would have to try and work the story around not mentioning that piece of information because some people felt that there should be no mention of “catolicism”. Think just how senseless the story would be without it (most of it would make no sense for the audience because they wouldn’t understand people’s expectation that he had no childen).
If it would make no sense for the story-teller to refrain from mentioning a specific christian denomination when it was key to the story, why would it make sense for the story-teller to refrain from mentioning a specific sexual orientation which is key to the story?!
