I don't think this is necessarily all lies. I can try to speculate on how the new system might work and how to translate the sales rep's statements...
My personal opinion is that the Marriott system will be an another exchange company Vistana owners can pay to enroll in (like non-mandatory resort owners pay II) and will likely have another annual fee. Perhaps this will be open to all at the same price, perhaps only to developer/retro purchasers, perhaps lower price to developer/retro purchasers and steeper price for resales. Vistana owners will be able to trade for Marriott points anytime before 8 months. At 8 months, if they are in VSN, their week is available to VSN owners for VSN trading. So if one owns a WKORV week, you can book it, trade for Marriott points thereby making the WKORV week available to Marriott owners, or wait for 8 months and trade in VSN. In such a system, I translate the sales rep as follows:
I was told the merger will only benefit Marriott owners = they would not have to pay anything out of pocket to trade into the new resorts. They would just see the new inventory then Vistana owners trade for DC points.
I was told that if you are a Marriott owner you will have the ability to transfer / trade into Westin / Vistana properties = if there is inventory, i.e., Vistana owners trade into DC points instead of Staroptions at 8 months.
But it will not let Westin / Vistana book Marriott properties = unless they pay extra to enroll in the exchange system. Or unless resale owners pay extra to buy points.
“Because MARRIOTT bought Westin /Vistana” “We ( Marriott) own them”= this is true.
They said it might take place by the end of the year = This is also true. It might... or not...
In the system I describe, a VSN owner who trades for Marriott points at 12 months out makes that week available for Marriott owners at 12 months out. But that's really not different than depositing a week in Interval and having someone on Interval get that week. Does that mean that fewer weeks will be available for VSN trading at 8 months? Probably, because owners will have another exchange company to deposit in. But, conversely, there will also be fewer owners in VSN looking for that VSN exchange inventory (a WKORV owners who exchanges Marriott DC points will not be competing for Harborside or WSJ inventory at 8 months out).
But that's all just speculation...