Who says no? We help Celtics and 76ers duck the tax and upgrade the Warriors' roster, for a fair price.
Logistically, the order would be the Celtics portion first, with our cap space, and then the rest of the trade—where, since we're sending out $60M, we're able to take back $75M, less than PG and JK earn. Buddy Hield's contract is only guaranteed $3M next year.
The optionality on JK (team option) and Simons (FA) next summer isn't bad either.