The reasonable answer to that is to regulate wifi frequencies world wide and modify weather radars if necessary. That would solve the interference problem while keeping the firmware open.
As I understand it, this was all known when 5Ghz wifi was introduced, so it was a trade-off (see the 2013 NTIA report for details). I don't think it makes sense for them to move all existing services in the 5Ghz band to a completely new band (which might not work anyway, due to the technical requirements of doppler windshear radar). It probably also wouldn't make sense to limit wifi to a small range of the 5Ghz band. However I'm not really an expert on this, so feel free to correct me.
Oh, and you can get freedom -- it's just the radio software that's the issue. The obvious solution is to make the radio software un-flashable, and leave the router software flashable.
Even the FSF is willing to compromise on that, as long as the locked software is hardware-locked and totally unchangeable by anything and anyone (including things like over-the-air updates), so it can be considered part of the hardware, and as long as it does not have access to main memory or can otherwise interfere with the free-software part of the system.