I would actually love to see a flamboyant/feminine gay man being written seriously in an action or superhero film. The natural inclination would be to make them sidekicks or comedic relief, because a feminine demeanor on a masculine figure is seen as the ultimate contradiction. But I think a good writer could make that work.
That being said, if Black Mask is gay, then it is kind of funny (in a not-so funny way) that the first superhero film to feature an out (or explicit) gay male character has him as the villain. Yes, gay male characters can and should be shown as villainous, but I would have preferred that happen later down the line after a couple of out heroic ones. Again, assuming the rumor is actually true or not.