So let's have the key discussion here that's at the heart of this episode:
If Rudy enters a flirts or even enters a relationship with a girl his physical age - ok or not ok?
First though is ofc: Rudy's mentally a 40something yo guy, so obviously it wouldn't be ok. But then you need to think about the situation: Rudy was reincarnated into this position without his choosing. What can he do ? Tell everyone that he's actually 40something? At best nobody believes him and thinks he's a weirdo. At worst he's killed, right after his parents forsakened him in disgust. If he somehow chose to become a kid, if he could repeatedly do that, then I'd say it wouldn't be ok. But as is? That's his life now, he was given that chance by some otherworldly entity, so it's not his fault. And ultimately, what's gonna happen? He's not a rapist. At worst he's gonna do something overtly perverted and get scolded for it. And once it comes to sex, he's probably a safer choice for any girl than other boys who know nothing about protection and properly caressing a girl instead of just looking out for their own pleasure.
All things considered: As long as he doesn't start sexual stuff at his current age, I find nothing wrong with fully embracing his new existence. And once he and the girls in that world are officially adults, then whatever. Then it''s at best age-shaming. "Oh no, a 40yo guy with a 16yo girl?!!! - except it's legal, so stfu.
@Ryll: I dunno. When Rudy out-argued his father, it felt ... bad. Like, his dad felt that something was off. Even if Rudy was in the right, it looked to me as if his dad noticed how that kind of situation shouldn't play out like that. We later saw them behave like father-son again, yeah, but I'm not sure if that scene has a negative long-term effect that's still hidden for now.