They already did in the first episode while trying out for the cheerleading squad.
Supergirl has been a huge disappointment this season. I watch everything off the net and just jump over the BS lezzy scenes. As far as the white and green Martian thing; both of them are black humans in the show so I'm not really seeing a racial aspect to that.
So far Sleepy Hollow, Gotham, and Grimm are doing pretty good at staying away from the forced pervert homo action. Others too but those just came to mind. Lucifer just had to go there an episode or two ago but it was just in passing; no two guys kissing crap.
Lots of ways to watch free tv and movies online if you have high speed Internet; here's one for TV but I've noticed that you have to watch the show fairly soon sometimes or it gets deleted from the servers and using Firefox with the Adblock Plus and the NoScript addons helps cut down on all the ad crap too. What I like best besides the free price is zero commercials. Just the 42 minutes of the one hour with ad's show.
http://project-free-tv.ch/schedule-tv/
They made the Penguin a homo in love with the Riddler in Gotham. That was it for me. Grimm, yes, has been pretty much free of politics or anything else. For a short while, I thought they were going to make Wu gay, but they didn’t.