It's less about Linux for me than about the other things I want to boot (MS is unlikely to disable Linux bootloaders on certified Windows PCs for lots of reason

It's less about Linux for me than about the other things I want to boot (MS is unlikely to disable Linux bootloaders on certified Windows PCs for lots of reasons). By way of example, the company where I work today produces a hypervisor for x86. We're nowhere near big enough to exert market pressure on someone the size of MS or the hardware manufacturers. When we recently added UEFI support to our product, we looked at support for UEFI secure boot as well. Some systems made key management easy (obvious bios options, etc.), but others made it impossible. Upon investigation, this mostly appears to be more due to apathy on the hardware vendors part than any conspiracy theory, but for an end user the distinction is unimportant. Today we can work-around this by using an MS-signed bootloader shim, but this reduces the security of the end solution (any ms-signed shim will boot, a third party owns the root keys). And, as I mentioned in my comment above, MS can change their policies at any time. I haven't run into an x86 system yet that doesn't at least allow you to disable secure boot, but the trend towards more locked-down hardware in general (esp. in mobile) worries me due to the potential for anti-competitive behavior towards both commercial and open-source software from third parties.