Given all the challenges WN's IT has, I think this is quite the reasonable restriction in exchange for the giving CP out in the first place plus allowing 3 changes.

Since the CP booking is last seat available, your risk of not getting a seat should be low, even if a high demand date, they are usually available a bit out, just at sky high prices that won't matter here.

Yes, it would be nice if they could "hold" a reservation and tie it to something. What about making the future reservation on points or cash then calling to have it switched at the appropriate time? I think I've read here that it can be done.