She allowed polygamy, she knew what she was getting into.
People don't necessarily make sound situations when they're in love, and it's questionable to say she knew what she was getting into. Imaging something and thinking you can understand it isn't the same as actually experiencing it.
Best we don't, unless it's official. We can do "cyborg_(sage(mami1210)" to identify him, but unlike Io we've never seen his name on dialogue.
Actually, the Artist has referred to him as ้ใตใคใใผใฐ ("Heavy Cyborg") in post #2902877, and does have a specific Pixiv tag now: ใใใ็ฝใใใชๆๆฉ็ณปใฎๆญป็ฅ (Sugoku Sawayaka na Kankitsu-kei no Shinigami, lit. "Very Refreshingly Citrusy Death God"), which obviously refers to the citrus-smelling polish that he now takes because Io loves its scent, but for some reason the tag is glossed with Koisuru Sentou Saibogu (lit. "Battle Cyborg in Love").
Fairly certain Cybro bribed the guard to just check his ID and not Io's. Hence "But I think you could do with something more up-to-date." and giving what looks to be some sort of credit card/chip.
