I don't think this pertains to homebrew at all, they're covered separately under part 15.23. The bigger worry is modified devices - devices that would have had

I don't think this pertains to homebrew at all, they're covered separately under part 15.23. The bigger worry is modified devices - devices that would have had a type-acceptance, but it's been invalidated by the operator. They'd be a grey area that becomes a much darker shade of grey under this interpretation. It does bring to mind a specific example I'd be morbidly curious in; the Icom M802 is a marine HF/SSB set that's popular in small craft. It has a neat trick where if you hold a specific set of buttons while you power it on, it can be operated in the amateur bands (until it's powered off, then it falls back to the factory behaviour). Under this interpretation, that'd no longer be legal? Since the operator has invalidated the part80 type-acceptance by enticing the unit to transmit outside of its intended bands, it can no longer be operated (by a ham operator) in the ham bands? Under my current understanding you'd need both an (unrestricted) radiotelegaph or radiotelephone operator's license to be allowed to adjust a part80 transmitter in a way that'd affect it's proper operation; plus a technician (or above) amateur endorsement to actually operate it in this mode, to do this legally. Under this (new?) interpretation, that's still not enough to be trusted? (A rather long-winded example, but one close to my heart. I believe it's one of the reasons this particular model lost its type-certification in Europe.)