From what I've read in the papers here the Dubs are "in no rush (no pun intended) to sign him" and will "match any reasonable offers" for him.
There doing the waiting game, seeing if they can get him at a discount.
If the Celtics has the MLE and offer it to him, which I think is a fair offer, doubt the Dubs might match it. I don't see them paying Rush 5 mil a year.