It's not about being gay, it's about toxic masculinity.
If you're not exuding some form of manliness in your average everyday life, then you're at risk of becoming gay. And being gay means being different, which is a HUGE no-no in today's society.
Does your giant pickup truck not have a faulty exhaust system that makes it really loud? You're gay.
Do you do cardio instead of just sticking to weight-lifting all day everyday forever? You're gay.
Do you not pick fights with random strangers at the slightest provocation, even something as small as them looking at you funny? You're EXTREMELY gay.
It's all part of a large toxic social stigma that's keeping men in men categories and women in women categories.
The man in this animation made the unfortunate mistake of "liking women" rather than "wanting to fuck" them. This critical error made most other men on the internet believe that because he likes women, he must like womanly things. And if he likes womanly things, he must be gay. And because he has now been declared gay, he must be relentlessly bullied into submission (or savagely beaten in extreme cases) until he learns from his mistake.