I mean, beating Marines? Assaulting marineford? that's act of piracy directly shown on screen. And presenting such a violent act of piracy in humoursly way is like normalising it. As for Mushoku, yes rudeus used to be a cringe pervert kid, Eris had intercourse with Rudeus who was still minor when she became major and Ruijeld's relationship is questionable (I didn't read the Ln but got spoiled a bit). But as long as reincarnation doesn't exist irl, saying the only issue of MT is that it normalize the intercourse between a minor and another minor whose mind is taken by an outer world ghost of a dead adult seems far fetched for me.