You can just ignore it. It will go away after a number of reboots...
Thanks for the reassurance! I tinkered some more w/ BIOS settings now, setting the OP changes again (and unchecking UEFI boot by accident) and after a couple of no boot device restarts the manufacturing message went away. Then I realized what I did and checked UEFI again, leaving the hackintosh changes in, and the message is indeed still gone.
Now the last thing I need to sort out in my bad LED behaviour since 036 (NUC6i5SYH in BIOS 0036 LED S0,S3 OFF. After sleep and wake - blue S0 ON.)