You would absolutely need to make sure that they bank the points if you made the offer, I think. A December UY would need to be banked by July 31, if I am understanding the contract correctly -- basically, this year's points are available, so they want a higher bid + this year's dues. If you had your offer accepted today, you'd be coming out of ROFR in June, then relying on estoppel and closing and everything to be in place in time for YOU to bank them, and it's fair to estimate 8-10 weeks from offer to points being in the account. Which is cutting it real close.
And I don't think you can rely on MS being generous about the banking deadline on a resale.
Given that the points would need to be used by end of UY if not banked and given what fall availability looks like, I wouldn't want to count on being able to rent them without having banked them.