So, it's not that technically there is a written rule about not putting Israeli flags as a profile picture, but common sense often matters more than knowledge of written rules that are meant to manifest common sense and not to hinder it, so I would just report the idiotic profile (you find the "report" button if I'm not mistaken) and leave it to those in charge to figure it out better. Thank you for noticing this particular one. I think we are all grateful that you didn't keep quiet.