Using this document, and going to this and entering a serial, it provides a message as depicted below:
"We’re sorry, we’re unable to check coverage for this serial number. Please check your information and try again. For help with Apple accessories, please contact Apple Support"
It does NOT say the serial is invalid, just that it cannot be checked.
Is this a sufficient message to say the serial is not in use, and can be used for the SMBIOS config?

Using this document, and going to this and entering a serial, it provides a message as depicted below:
"We’re sorry, we’re unable to check coverage for this serial number. Please check your information and try again. For help with Apple accessories, please contact Apple Support"
It does NOT say the serial is invalid, just that it cannot be checked.
Is this a sufficient message to say the serial is not in use, and can be used for the SMBIOS config?