A prominent warning message makes complete sense. Being unable to disable it does not.
Microsoft used an existing UEFI feature to guard against attacks even when your Admin account is compromised. I consider it to be a good thing. I'd want as many clueless people to enable secure boot as possible.
The only time the messaging is useful is when someone has unintentionally disabled secure boot. In this case they can go enable it again (or bring it to geek squad, etc).
If the user intentionally disabled it, then the it should be possible to suppress any warning messages about it.
If malicious software somehow disabled it, it can probably also make the registry settings tweaks required to hide the messaging so the user won't know anyway.
I don't know the answer to that question, but if I was a malware writer, disabling that warning would be the very first thing I would do.