There is no way of querying secure boot or using it for DRM. All you can do I report if secure boot was on or off.
b) corporate lockdown of hardware in the hands of employees where they don't want to give root
That could be as well, but we already had non-secure boot options for that.
See a) Saying something wrong twice doesn't make it right, it makes you twice as wrong.
d) letting manufacturers or OS vendors control the machine you paid money for
Manufacturers have no control over secure boot. The implementation requires the keys be able to be managed by the user. You just jump into UEFI and delete Microsoft's key if you want and load your own. It's no more giving someone else control than a website that suggests a strong password.
No that's not, you missed what Secure boot does.
You actually said a few right things there. Yeah it has nothing to do with hardware attacks, it has to do with persistent attacks.
But "persistent" means "past wiping the drive and doing a full reinstall"
No. The assumption for any computer is that it boots into a known configuration. Persistent in this case means it is impossible to remove from the OS. At no point has the definition included your "nuke from orbit" approach.
If a virus compromises a user's account, that's the actual harm done already, not reinfecting the machine.
Viruses can be removed and cleaned from machines. At least the ones which aren't following the correct definition of persistent. Damage in the modern definition is continuous and ongoing. Just because you've been infected at one point in time doesn't mean it's game over.