Because the system probably is seeing that the bios is already up to date according to the update servers. You shouldn't use automatic utilities to update the bios anyhow. Manual methods, by going and physically verifying with your own eyes, that there is not a newer version available on the motherboard product page, and updating it yourself, is always going to be the preferred method anyhow.
The Intel management engine interface shouldn't have anything to do with the UEFI bios anyhow, which is firmware and is entirely independent of the operating system.