Haha, I don't remember the last time I was this disappointed with the reveal after clicking on a clickbait-y title.
Westbrook is just a hard player to integrate into most teams since he needs to dominate the ball to be most effective. We already have White or Holiday in the game most of the time, and Tatum is going to be controlling the ball often in the non-Brown, non-starters minutes. Even if Westbrook said he was happy to be off ball, his poor outside shooting would affect our spacing and inevitably the defenses would be designed to force the ball back into his hands. If we do have a non-shooter on the court, I'd prefer it be a really versatile defensive player with some size, which is why a guy like Lamar Stevens makes sense if he works out.
If we didn't have Holiday, I would actually be more open to the idea because we know this team has always needed elite ballhandling. Imagine Westbrook handling the ball with Brown, Tatum, Porzingis, and Horford or White out there as shooters. Maybe it wouldn't be as good as a true 5-out lineup, but it would still be an interesting look. I just don't think that with White and Holiday already here that Westbrook can fit in, however.