It is true actually.
The only other
DVC "inventory" they have besides the undeclared inventory is rooms that they have booked with their own points that they still own, get from cruise swaps, etc. that they are trying to rent out for cash, use for welcome home stays, etc.
So in your case they may have already used some of their own points inside of 11 months to secure that room to rent out (because the poly is popular and probably rents well), then later offered to use that room to fulfill your welcome home request. Once a room is declared it has to be booked according to DVC rules, even if it is being reserved by DVC themselves
That is not the same as them holding a hard to get declared room ahead of the 11 month window for someone, that would be against our contracts and would land them in trouble.
Otherwise everyone would be asking for AKV Value or Club studios, VGC rooms, etc. with every direct purchase and they would NEVER be available for owners to actually book