I think my point may have gotten a little muddled with how I said it
My point was that Universal isn't going to concern itself with catering to offsite guests, including vacation package holders, in planning a transportation system. I don't think they would bar anyone from using it to travel between the parks, but they most likely wouldn't have (or at least want) any deticated off resort stops. So any offsite vacation holders would have to drive or shuttle to the park itself before having access to the monorail... You know, if it ever actually happened.