I don't believe it's accurate to say there's "no real reason", it seems like enforcing this behaviour is very much aligned with the goal you've posited.
This is under the assumption that this was indeed done for the purpose of ensuring Intel specific drivers are used for power management purposes.
Hiding the option from BIOS menu is absolutely enough to "ensure Intel specific drivers are used for power management purposes". It would be annoying, but workaroundable. There is no real reason for anything more, aside of being able to get months of complains about not releasing a one line fix allowing your customers to use your hardware.
It absolutely is not enough, because I can come up with a single contrary case.
If this change was made in a BIOS update, simply hiding the option would leave some users stuck in the "wrong" setting forever. So one might write some code to flip it back at the same time.
This is the simplest way of fixing the problem. It doesn't need any assumption of maliciousness or incompetence. It's just unfortunate for Linux users, since they clearly didn't get any consideration when this fix was written, that's all.
Aside of that, this couldn't even be a change made in BIOS update, because every OS installed earlier, including preinstalled Windows, would stop booting without being provided with Intel driver.
Writing a piece of code that resets that one particular variable on each boot?
Sorry, but that's just nasty. There is no reason to do that if the goal is just to provide best experience on supported OS.
Although I agree that it's unlikely this was targetted specifically against GNU/Linux and other OSes. The most important thing would be that Windows 7, 8 and older won't boot anymore.