Very interesting.
Personally I wouldn't go into business with your coworker, because it would necessarily compromise my sense of, let's say, 'honour'.
I have a rule: Don't reward cunts
And it might be extended: Don't reward them, don't behave as if they are good, don't validate their bullshit; be hard and unmoved; disdainful and inhospitable.
That's just my take, and be aware that it values personal principles over social/professional success, and an approach like this will make your life harder (it did mine, but it also made it more fulfilling).
Now, the key thing to this is that very few people are 'actual cunts' who need a cold shoulder like this to help them reassess their lives. Most common cuntishness is just good but insecure people adopting cuntlike behaviours temporarily, and they have to be handled with more care; more like a parent. Confront the behaviours outright with these people and tell them what is and isn't acceptable.
Also, don't listen to me I talk shit and can't tell you if this works in the long run or not.
By the way I got Owl for my spirit animal.