I'm not sure the scenario you use would directly result in weeks being freed up to exchange in II. Trust points owners who want to go to weeks-based MVC resorts would be reliant on weeks deposited by enrolled owners into the MVC Exchange company, not II. They do not have a week to exchange, only points. The only way a Trust owner can access II inventory is to convert their Trust points to II exchanges (for example, 4000 DC points gets you a 2BR in II with a TDI of 115-135), but I think my understanding is those II exchanges using DC points have to be to non-Marriott resorts. In that case, where a Trust owner is exchanging to a non-Marriott in II, Marriott does have to give II a week from somewhere in the MVC system. Not sure how often points are exchanged for II non-Marriott trades, but I can't imagine there are that many.
Having said that, I do think some Marriott Waikoloa inventory will show up in II (I think some have already reported seeing the inventory there), but that may be because MVC has great discretion in what weeks they give to II when they control the deposits, and they have an incentive to try to get non-owners to come through the resort to provide prospects to the sales organization. As long as they have unsold Trust points, there will be units controlled by MVC that are in excess of potential demand from other points owners, so that gives Marriott some flexibility as whether to make those units available in II, for cash, or even additional deposits into the MVC Exchange to benefit MVC points users. As a result, I suspect they allocate some percentage of the inventory at Trust-owned resorts for II deposits. I agree that there may not be many Waikoloa II deposits, but I think MVC does have an incentive to find ways to deposit some Waikoloa inventory into II.