Generally, in the USA, a modification, temp or permanent, that defeats a built-in safeguard would violate a warranty--if the manufacturer knew about such a mod.
But this all seems too desperate too soon. I'd think somebody who depends on highest quality 4k video would have dedicated equipment.
No Life Digital proved that there's almost zero difference between 4k HQ and 4k non-HQ when you apply a bit of sharpening in post (or use clarity slider).
you simply can't tell the difference even looking 100% at the stills snap from the 4K output. Video processing follows really the same rules as photography - we all know we can't just take default JPEG out of the camera and not sharpen it to get the best out of it. so why would video be any different?
which actually makes sense. downsampling is a natural "sharpen", so applying sharpening to the non HQ version, simply makes it for all purposes, very similar. You get line jaggies because line skipping but zero people are going to see that on video.
IMO too much is made of downsampling without knowing the real difference that it can achieve. There may be better color fidelity,etc but how much would you actually see on video versus a still image that you can subjectively look at for minutes?