Aren't those illegal, though. Where I live, they technically are, at least, although it's rarely enforced. But they can ban it with that argument. On the other side, SonoHana also could be considered illegal for featuring pornographic content with underaged girls.
In the US they’re very legal, purely fictional depictions not based on real events are protected speech.
They wave their hands in the post about whether or not they care about laws in other regions without saying anything concrete, so it could be they just select whatever country has a law banning a particular topic like homosexuality and remove a game globally for it.
Regardless, I think those games will always exist and I don't know if steam banning them would help much. What they need is make sure those games won't be recommend for kids, and a filtering for mature games technically should help with that (not the "what is your age" bullshit, though). The problem is in banning some games with shallow motives and allow other worse things to be in the store.
You could argue that GTA is homophobic and mysoginist, for example, but they would never ban it.
If they decide "we won't ban anything at all", at least they stop being hypocrites. What they're saying is that they won't endorse or condemn any game in the store, since they're just a store.
You endorse something by selling it, if I buy beans at Walmart and when I open the tin it’s actually human fingers I get a refund from Walmart and they stop stocking those beans. They also don’t allow me to just come into the store and start selling dubious oils and radon, and certainly don’t let me sell knockoffs of other real products they sell in the store.
If you sell something you are endorsing it, that is how commerce works, if your endorsement doesn’t mean the coffee grounds aren’t full of glass shards people will shop elsewhere.
