Google and most companies policies in case of child sexual abuse is to nuke everything from orbit. Anything related is not worth the risk from their perspective that abuse or sharing of abusive imagery continues. They do NOT want to be hauled into court to explain why they banned a pedo's main account but didn't ban their alt account which they continued to use to abuse kids.

It is out of an abundance of caution.

Even if every single one of them was a paying Google subscriber to the tune of $20/mo it wouldn't likely be worth the risks in terms of cost/benefit analysis from Google's point of view.

I sort of wonder how the accounts are connected. Like sure there is a social graph but is it really SOP to nuke the social environment around suspicious accounts?

Were they all logged into the iPad?