As a parent of young children, this is your entire problem:

> the terms of engagement are, I can block it however I want from the network side, and if he can get around it, he can watch.

You're treating this as a technical problem, not a parental rules problem. Your own rules say he's allowed to watch!

You have to set the expectations and enforce it as a parent.

Depends on what the goal is. But yeah I agree if you really don't want them on YouTube (or whatever) and really do want them to tinker with their devices then you're likely going to have to eschew technical measures for more overt ones.

I think the point is that it's not enforceable.