Far from it. His issue is his confidence basically. His physical abilities are 2nd only to Saitama and, maybe, Blast.
Hell, the acid left a flesh wound on him, but considering that it instantly melted everyone else, it's still impressive.
I mean, yeah.
Darkshine is an exaggeration of a body builder, right down the questionable rendering of the tanning oil. He grew a few feet due to excerising, so what? He's in the company of ninjas who can train themselves to attack faster than a millisecond, a prisoner who can grow their hair instantaneously to protect their naked body, and a samurai who can atomize whatever he cuts with sword swings.
All impossible to achieve in real life, but they are still portrayed as humans. They canonically trained themselves to reach those ridiculous heights.
Pig God is questionable, but he's an unknown and has been still presented as human up to this point.
You are on to something that I can't get into, but it's not solely appearances that determine one's monster hood.
Look at Garou. He's a regular dude who is literally walking the line between becoming a monster or remaining human. He's not committed, but he was still sought out while being a straight up human. Hell, he did not even have explicit powers like Homeless Emporer
He just beat up a lot of heroes.
Maiko, Homeless Emporer, Psykos, and that sexy Dom chick all pass as human, moreso than a decent handful of S Class heroes, but they wouldn't join because they are presumably too far gone to even pretend they care about people.