Unarmed:So what do you think is this a none issue or might it actually occur?
I think it's very much an issue. Remember that only an unrestricted account has to start the game, as far as I'm aware. Then Little Johnny signs in on his silver account that isn't allowed to buy the game and accidentally hits the Buy Trial button (or maybe intentionally hits it). He's signed in to LIVE, but not allowed to buy content and the game crashes.
and/or is there a way to set this flag for our own account?
You will have to make a second account that has LIVE privileges (the free silver account works) but is set to be a child account that cannot buy the game. Then you just make sure that only your CC enabled account is signed in when starting up the game, sign in the other account on another controller, and use that controller to hit the "buy game" option.