IAmSinistar: Looks like they are slowly fixing
Juggernaut. It now shows that you need the base games to play. I'm guessing it was never intended to be a free upgrade, and hence why there were some problems with it. But if it does appear free later, that's fine too.
yyahoo: I guess I'm missing some backstory. Was it listed as free for a while?
Apparently it appeared on some folks' shelves, but without any downloadable content. So this led to speculation that it was a free add-on. GOG has reported having a number of problems adding it to the system, to the point where they needed to code a special solution for it, so its final form is still a mystery.
I'm holding off on buying it for now, in case it is meant to be free. Also, a purchase now while it's in flux is a bad idea.