>That screams anti-competitive behaviour to me

...or they're trying to increase security against physical attacks. The year of the Linux desktop has been a running joke for decades. Microsoft doesn't need disk encryption to keep Linux from gaining traction. Linux is already doing a pretty good job for them.

Well, I could see plenty of other use cases (i. e. "My machine is kaput, can you tether the hard disc and grab my data") but this one has a legitimate business edge if they intercept it.