Well, 1) the character isn't Superman, 2) he's bisexual, not gay (there's a difference, which they don't recognize in Texas, because the cowboys gun down both groups with equal fervor), and 3) there's no longer any firestorm of outrage when a TV/film character is shown to have other than "normal" sexual orientation.
The conservitard asshole TV show host Mark refers to is just trying to get his audience ginned up by turning purple and screaming in fake outrage about this. The truth is, no one really cares, except the lonely, aging, impotent old white men who sit in their basements, watching this shit. There are enough of those people (to use "people" in a broad sense) to keep these shows afloat.
Our resident conservitards respond eagerly to all these dog whistles. Whatever they post is always a direct feed from the conservitard outrage media, usually within the prior 24 hours. I guess when you're lonely, sad, deteriorating physically and mentally, and no one will talk to you because you stick bigotry, race hatred and conservitard politics into every disussion, getting worked up about stuff like "gay Superman" is the only stimulation you have.