It could but when the Trust has all of the assets, and the personal property of the estate in the WILL is less than the State requirement for probate, there isn't a need for probate. In my state the minimum State requirement for probate is $100,000. In this scenario the timeshares are personal property outside of the Trust. The object of the trust is to secure all assets, not liabilities. A timeshare is a liability, imo. If the timeshare is actually wanted by a family member they can still have it outside of the Trust or it eventually gets taken back for lack of maintenance fee payment. The repossession of the timeshare can also happen while the owner is alive if the owner decides to stop paying the maintenance fee without affecting the Trust assets only when the timeshare is held outside the Trust.
Again, this isn't legal advice and some people would consider this timeshare disposal strategy to be unfair to the developers but in a way it's the developers own fault for their inability to provide an exit to ownership.
Bill