It's much easier to simply use this with whatever date you prefer:
defaults write com.apple.SoftwareUpdate MajorOSUserNotificationDate -date "2030-03-03 12:00:00 +0000"
I've got that in place and still get the Tahoe popups, so there's some other mechanism here.
I've got that in place and still get the Tahoe popups, so there's some other mechanism here.