I don't think they implied that the chip should be read only, you should still be able to have a flashable firmware of some sort. But instead of giving this ch

I don't think they implied that the chip should be read only, you should still be able to have a flashable firmware of some sort. But instead of giving this chip which should be read-only regulated by software direct access to the bus, route it through a bit of extra on board circuitry which physically prevents it from writing data to the bus. This would enforce the readonly client in hardware, not firmware.