Okay, first: I'm not a "bro." I'm a woman. Just gonna like... put that out there. Second, wtf is "pro gay power"? I'm an ally of the LGBTQ+ community, if that's what you mean? Third, as someone already stated, odds are that the kiss MC saw was a stolen kiss and they weren't expecting anyone to see it.
This: "You act like being gay is bigger than everything else. From those i know, they just want to be treated like normal people, and to be honest, being gay in our society ain't that big of a deal anymore." is not accurate, neither about what I've said nor how society is.
1. Me stating that I think MC would be a complete asshole if he outs Chad isn't me not treating gay people "like normal people," it's me stating that it's fucked up for someone to out a gay person who isn't comfortable outing themselves - which is a unique situation that straight people don't have to deal with because nobody's sitting around a dinner table like "Mom, dad. I have to tell you something... I'm straight." Heterosexuality is treated like the default. Therefore, the topic of outing simply doesn't apply to straight people, so yeah, it's specific to people in the LGBTQ+ community. Hell, why don't you go ahead and ask "those you know" what they think about someone outing a person who's not out yet?? I'm sure they'll say that's a fucked up thing to do to someone, especially as an act of petty revenge.
Also, gay people don't need to be treated like normal people, because they are fucking normal people, but I'll just chock that up to semantics.
2. Obergefell (the Supreme Court case that made gay marriage legal in the U.S.) was decided in 2015. That's less than a decade ago, and that decision wasn't unanimous, meaning there were Supreme Court justices who disagreed with the idea that gay marriage is a fundamental right, even though heterosexual marriage is a fundamental right. The Pulse nightclub shooting was in 2016. The case about the baker who refused to make a wedding cake for a gay couple was decided in 2018. If you seriously believe that a country that still hasn't resolved issues with the Black community stemming from slavery has suddenly embraced the gay community after ostracizing them for... a very fucking long time... then I really don't know what to tell you other than that's a pipe dream.
3. If Chad doesn't want to hide anymore, then good for Chad, but that's Chad's decision to make and no one (including the MC) should be taking away his ability to make that decision. And trying to make him talk to anyone about it before he's ready to do so is also an asshole move. Those things need to happen when he's ready. Sure, MC can speak to him privately and say "Hey, I saw you in the locker room," offer support, and say he'll go with him to talk to someone or help him tell someone, but MC really shouldn't be dictating that. It's not about whether or not telling Sage will make it so everyone knows (although, there's always a risk there), it's about whether or not telling Sage is something Chad is ready to do.
4. "Second, if the MC decided to say fuck it and out him, well, he would be perfectly justified." No. Just... no. Getting beat up by someone is definitely not justification to broadcast private information that can potentially implode someone's life. And like... That whole paragraph is just super problematic.
I believe that there is no circumstance in which it's justifiable for MC to out Chad without his consent. And yes, this is a hill I'm willing to fucking die on.