Hardware vendors of budget laptops have already shown that they are willing to go to the effort of adding anti-features to their products to, say, disable hardware virtualization. I am second guessing why, but one reason might be that they want you to purchase a higher spec model with a higher purchase price if you want to use such features. (Shenanigans like this are nothing to do with Microsoft).
Could the hardware vendors to the same thing with locked keys. They (the hardware vendor) makes a choice that they are only going to support a restricted set of Microsoft Operating Systems on some of their products. They might believe that this would reduce their support costs because they don't have to deal with returned machines where the user has wiped the microsoft keys, bricking the device. It would also provide them with an opportunity to sell the customer a different model where the keys are not locked down, at a price premium of course.
You say that Microsoft's current rules would forbid such activity. That's welcome but Microsoft could change the rules in the future.
The vendor is choosing not to ship any free software so free software licences are moot.
I am trying to think of ways for the hardware vendor to do evil things.