You're probably right, but I don't see the harm in making firmware Affero GPL. For instance, intimate communication between two programs tends trigger GPL provisions. So there's an argument to be made that if a competitor improves the firmware for another device with a different cloud-powered backend, then that backend code must be released if the firmware is Affero GPL.

But my original thought was that maybe there's some useful logic in the firmware that's extracted to cloud. And on that point, it's pretty speculative.