Though from perspective of someone who is not reading the manga and does not know she doesn't swing that way, he isn't even bad or scummy, dude's doing what the gathering is intended for - trying to hook up with a girl.
He first tried to pressure Rika into drinking. Later, when Rika was trying to leave, he grabbed her arm and tried to make her leave together with him. Even if mixers are intended for hookups, Rika didn't show any interest in him at all before she tried to leave. She was also obviously scared when he grabber her arm, and even said no, but he didn't let go of her arm until Natsuko appeared.
He was creepy, scummy, and rapey, regardless of Rika's sexual orientation or relationship status. Showing up to a mixer does not equal blanket consent to sex with any and all other participants. He either failed to realize that Rika was not interested in him, or he simply didn't care either way.
last edited at Jan 2, 2023 5:14PM