Fan Support/Attendance
While fan love and loyalty might not mean much to NBA front offices (see Blake Griffin trade), OKC fans adore Westbrook. He has become the face of OKC basketball ever since Kevin Durant left for the team that just beat them.
Westbrook was supposed to lead them to deep playoff runs every season, or even a title, none of which have happened since Durant departed. OKC trading Westbrook would be a gut punch to the fans and the community.
According to NBA.com, going into the 2019 postseason, OKC has sold out an incredible 384 straight games at Chesapeake Energy Arena. While I am not doubting the incredible basketball city that Oklahoma City has blossomed into, you have to wonder if ticket sales would go down if the product on the court was not a playoff contender.