The nagging might be enabled by the IT support of the company you work in. Mine is also not nagging but the company one used to do it quite often

It nags by default. There is a plist setting to turn it off though.

please do let the mere mortals and linux refugees know ! thank you !

ok, finally got a chance to look at it in some detail, and here is the scoop:

let's see what the values are ?

    % defaults read com.apple.SoftwareUpdate

this gives me:

    {
        AvailableUpdatesNotificationCountKey = "-1";
        AvailableUpdatesNotificationProductKey = "MSU_UPDATE_24G90_patch_15.6.1_minor";
        MajorOSUserNotificationDate = "2032-12-31 23:22:47 +0000";
        UserNotificationDate = "2032-12-31 23:22:47 +0000";
    }

ofcourse those are modified values, which is done like so:

    % defaults write com.apple.SoftwareUpdate AvailableUpdatesNotificationCountKey -1
    % defaults write com.apple.SoftwareUpdate UserNotificationDate -date "2032-12-31 23:22:47 +0000"

you get the idea.

with this, i don't see the nags just yet, but probably it is a bit early to conclude ?

Sorry I didn't see this earlier, but yes, that's the settings I was referring to.