It might be because you were signed into Windows that it completed the BIOS update.

@bradthetechnut​ Yes I was logged into Windows when I received the Windows update alert just as I am when I run the Dell Command Update application. Microsoft should not know the password for my BIOS so how is it that they were able to update my firmware without it. Dell Command Update asks for the password but fails to apply the update. I always download the installer to update the BIOS and it too asks for my password. Dell documentation left me with the impression that if I applied a password it would protect my system from unautorized updates or changes to settings but apparently any hacker with the knowledge are able to.

I should also point out that I always time firmware updates when the weather is good to minimize the chance of a power failure during an update which would potentialy render my system unbootable. Since Microsoft does not ask permission to install the update this could be a problem. Luckily, today we had good weather so just by chance the update succeeded.