You can't expect that to be taken seriously when out of persona 3-5 (admittedly assuming on 5, I got a bit over halfway then my ps4 hard drive failed and I've not restarted yet...), he's the closest any non-mc gets to having a canon love interest with Naoto.
At most you can maybe argue he is Bi. But if p4 has a gay character in the cast, it's Yosuke if anyone.
Dingdingding. If they had never cut out Yosuke being romancable(the lines were voiced and everything, go youtube it), I'd be 110% OK with his casual 'hurrhurr' homophobia, because it'd have made Yosuke the most human and relatable character in the cast to a large number of people who have bashed gay people in the past out of ignorance and misconceptions but don't hold actual malice in their heart, whether they've grown out of it or not. And even more so for those who remain in denial about actually being gay. That said, Yosuke, even if he isn't gay, is still one of the best written characters in video games. Yes, despite his gay bashing, and actually, because of it. Hear me out.
When was the last time you played a game where the characters weren't perfect, and what flaws they had were superficial and quirky, something that could be played up for laughs? For example; Ryuji from Persona 5 is a loud hothead and can be simple at times, but you know he means well. He can be Japan-style anime pervy at times, but through his interactions with Ann and the others over the course of their social links/main plot, you know that he clearly holds respect for them. In other words, Ryuji is only flawed when comedy demands it. Otherwise, he's perfect in his own quirky way. He has no serious personal failings. He's handsome, he's likable, and he fills a niche in the Phantom Thieves.
Alright, now Yosuke. He's friendly, he's likable, he never lets you down. He's the right hand of Narukami throughout Persona 4 and the guy who acts as the voice for our otherwise semi-functional mute of a protagonist. He bickers with Chie, he has a pervy side played up for laughs (fucking awful Golden addons aside). But, and here's the thing, despite how likable and reliable he is, he has a pretty obvious flaw. This dude just won't shut the fuck up and take some social cues when he gets annoying to others. This ties into how his joking about is how he tries to be personable and likable to others in his social link, but eh, spoilers. This is shown in his constant bickering with Chie, with how Saki seems to have very little patience with him, etc. But most notably to a lot of people, is how he plays off Kanji's insecurities to crack jokes. Whether Kanji is gay or not, that's for others to debate. But Yosuke has a) No ability to tell that he's crossing a line and b) Zero actual malice behind his actions, just his own insecurities being projected.
Because as we know, Yu and Yosuke are tight. They're besties. And considering the content that was cut, Yosuke has some feelings for Yu that make him uncomfortable, even if there's no actual confession in the end. Yosuke's homophobia is based in insecurity, combined with his need to constantly keep people laughing resulting in bad jokes that just make us all shake our heads in frustration. Yosuke is the most human member of the cast because of it. He's obviously flawed in ways that can objectively be changed for the better. Unlike Yukiko(that quirky laugh!), Chie(MEAT!) and Teddie(I was raised in a TV World by my Sensei!), Yosuke's obviously flawed despite having redeeming qualities. And based on Yosuke being clearly displayed as good-natured, it's a safe bet that with time
he will change. It'd be nice if he did it over the course of Persona 4, but then, isn't that too easy? Persona 4 is already bordering on wish-fulfillment where the protagonist is the cure to everything wrong with everybody ever, what's one more thing, right? Eh. Come now. Are you telling me that you've outgrown serious personal failings in the span of 8 months? We should be applauding the Persona team for having restraint in fixing
everything and not inching the protagonist deeper and closer to Marie Sue territory.
So in summary. Yosuke's probably the best portrayal the team has ever written of an actual teenager, because he has very obvious failings despite his general good nature and likability. He's childish, he's insecure, and he's casually homophobic. By the time the game ends, he's clearly striding to overcome all of these things. I like Yosuke despite all of these things, and I appreciate Yosuke all the more because of it although I'll admit that it comes across as an accident that he turned out well, rather than actually intentional without the added context of the cut content. That said, I'll defend Yosuke's homophobia, but I'm not touching Japan's 'teehee boobies, bathouses, panty shots' bullshit that he, Teddie, and occasionally Kanji dip into with a ten foot pole. There's teenage stupidity and childishness over sex, then there's whatever the hell Japan keeps peddling in manga, anime, and video games. And it'll be a cold day in hell before I express anything but disgust at Atlus' portrayal of gay people in Persona 5.
EDIT:
Yosuke is only written well if we could actually rebuke him.
As it is persona 4 is a passive endorsement that his behaviour is just boy being boys which is a fucking destructive narrative and entirely against the message of persona 4.
This is also true to an extent. It's frustrating and stupid that you can't challenge Yosuke's childishness, and to a lesser extent the others' acting out. It honestly feels at times that the more you analyze Persona 4, the more some of its highs were accidents and in no way deliberate. My interpretation of Yosuke is easy as hell to overlook when taking him at face value.