Of course you can, just ignore it, and pretend it isn't there. Don't even load its drivers. Because of dark silicon, you won't be able to fully light up the chip anyway. Use the GPU being off to clock other parts faster if you want. You still get an unaccelerated framebuffer if it has the same arch as every other chip I've seen with a PowerVR for the past twenty years (Dreamcast, BeagleBoard, iPhones, PSP Vita, the MIPS board they came out with that I'm forgetting the name of).
>Because of dark silicon, you won't be able to fully light up the chip anyway.
If it's a separate chip, that's better, because I can cut power to it, or outright desolder it.
Still, I'd be uncomfortable having paid for a chip I did not want. Much like being forced to pay for Windows when buying a laptop to run netbsd on.
My point, if you missed it, is that this is not the sort of purchasing experience those who'll pay extra coin for a board with a slower chip that's also less power efficient just because it's more open would actually desire. And thus, it is not sensible to include such a chip.
The problem is that I can't, and most people who care about freedom and thus could be interested in a slower, more expensive board... can't either.