Ask HN: Is it possible to execute options but then sell the shares to employees?

More specifically, is it possible to leave a startup, buy the equity available to me through my vested stock options and then sell part of it back to current employees of the same startup?

I don't see a reason why not, but maybe I'm missing something. At the end of the day, once you trigger the stock options, you receive a physical stock certificate that you should be able to do as you please with...