It is strictly salary. Either he or Green would have to go in a blockbuster
Wiggins has done what the Warriors asked if him since the trade. But the Warriors cannot deal Green even if they wanted to because of Steph. So the stay near the cap, they have to shed Wiggins and Wiseman in a deal for somebody like Lillard.
I personally do not like the Lillard fit. 31 years old, questions of offensive versatility (playing off the ball in Kerr's system), and defense are issues. I like LaVine more. 4.5 years younger. Some versatility defensively. Can play off the ball. Can bridge gap between Steph/Klay era and whatever comes next