The Software Freedom Conservancy disagrees, and they are the main enforcers of the GPL these days, especially for Linux.

https://sfconservancy.org/blog/2021/mar/25/install-gplv2/ https://sfconservancy.org/blog/2021/jul/23/tivoization-and-t... https://events19.linuxfoundation.org/wp-content/uploads/2017...

Basically every IOT/router/phone/whatever which is advanced enough runs Linux and almost every one of them enforces firmware signing. They'd have to fight the whole world at this point.