Sort of. I'd imagine the hypothetical company would need to do a clean room reimplemention of the ROM rather than a straight rip since distribution of the ROM images is expressly forbidden in the TI license. That seems potentially hard, but not insurmountable, considering the relatively small size of the ROM. And then you get the rest through the emulator.
Although it'd be interesting if the calculator had a one-time flashing capability that allowed you to load an emulator once and then make it immutable and there was a way for schools to inspect what was loaded.