said by Spare Me :Uh...no they can't, that's a law suit right there. Maybe it's not simple enough for you. In order to qualify for HBO GO all that is needed is a subscription to HBO through a participating cable provider. They can't turn around and say "Well you have HBO, but not in a qualifying package of our choosing" They can't do that.
I had the IO Silver package, grandfathered with HBO. CV moved HBO to the IO Gold package. It later made HBO On-Demand available free to HBO subscribers - but not to the folks who had HBO grandfathered on the Silver package. So yes, they can do whatever they want.