Thinking about it, the App Store must be connecting to your iMac at some point and for some period of time or your "2" wouldn't be there in the first place, so perhaps you ought to think around visiting the App Store and visit /Apps/System Prefs/App Store and allow El Cap to d/l and install the updates for you. Yeah, you may not necessarily want them, but coming directly from Apple they won't do you any harm, and if you're really hot to get rid of the "2", this may be your only way.
CAVEAT: You've got no idea what your missing updates are
(*), so you've got no idea how long the d/l's will take nor how much they'll drag on your browsing while in process, nor do I know if they can be halted once they've begun.
Now there's a Catch-22 for ya!
(*) Since you've d/l'ed the iTunes and Security Updates directly from Apple, I don't think those remaining are likely to be very large, but that's just a
wiiild guess.
