It is: disable CH encryption because the owner of this device, to whom we are leasing connectivity, has set the "isChild" flag for this device to true in her account with us so that we can filter the Internet for this device.

There's no such standard signal right now. But I'd prefer such a signal strongly over code that I cannot control running on my own device to enforce legislation. If we're going to enforce these things somewhere, code on my devices is the last place I want that enforcement to happen.

> ...and why would any device respect it?

Because if they do not the ISP drops all further packets and the connection dies.