This should not happen. Owners of the Trust can book only what is held by the trust at 11 months out. If the trust holds 2% of VGF points, the most that trust point owners should be able to book is 2% of the VGF inventory as a "home resort" (I put 2% which is about 1/50, for reasons I that should hopefully be apparent below).
For simplicity, I will ignore that the cost to book a stay varies by date. Where I think the "gray areas" are (and where I have experienced adverse consequences in the Marriott ecosystem as a "legacy weeks" owner competing against points "owners") is how that inventory gets allocated. For example - what is "2% of the inventory"? Does the trust get 2% of the available inventory for each calendar day, and if it fills up that's it? Or could trust owners in theory all reserve Easter week (1 week out of 52) and nothing else for the rest of the year, and traditional points owners get shut out of that week completely?
With Marriott, where legacy deeded weeks owners book a full week and can usually check in only on Friday, Saturday or Sunday, I have noticed that since the points system was launched it 2010, it has become increasingly difficult to get Saturday checkins, which happen to be the most preferred. And, as a multiple week owner, I can book some weeks at 14+ months out, and yet still get the "no Saturday available" answer. There is zero transparency on how the trust gets inventory (i) when points owners try to book stays, or (ii) when legacy weeks owners elect to use points via the points exchange system.