defaults read com.apple.SoftwareUpdate MajorOSUserNotificationDate

=> 2025-03-08 01:16:42 +0000

defaults write com.apple.SoftwareUpdate MajorOSUserNotificationDate -date "2050-03-08 01:16:42 +0000"

defaults read com.apple.SoftwareUpdate MajorOSUserNotificationDate

2050-03-08 01:16:42 +0000

Hopefully this works, I'll upgrade to Sequoia when I damn well choose to fuck.