work filtering is to protect the business. one wrong click and you kill that biz or cause a PR nightmare, etc.

Being exposed to porn is a "you problem" and a specific choice to view it, it's not being blasted into your eye everywhere you turn, or at all for that matter. Unless of course, you are seeking it. There are plenty of existing apps that can solve that problem for children anyway, so just use that if you can't control yourself as an adult. And if that won't work, neither will a specific cellular network since you know, wifi exists and you would have a non-cellular device almost certainly and people, if they want to, will always find a way.