My guess is that Presti sees the writing on the wall, that Westbrook is unlikely to re-sign long-term after next season, so he decided to raise the stakes. If you're going to go bankrupt if you lose either way, you might as well increase your upside if you win. If Westbrook leaves after next year, having Oladipo (who wasn't very good and never has been all that great) and Sabonis (too soon to know for sure, but his rookie season was absolutely awful) is not going to change your franchise outlook at all.
And, in the tiny chance that George hits it off with Westbrook and the team overachieves and does something like make it to the Western Conference Finals, maybe both guys re-sign. It's probably a little better than holding onto two mediocre assets and ensuring Westbrook leaves.
