Of course that could start a bidding war, and draw more attention, and no doubt encourage more hackers... so actually never mind, probably a really bad idea.
A 10k bounty to not release this might stop a few people from doing so, but all it takes is for a single individual to say "fuck it, I have a steady job and a nice place to live, giving MS the finger is worth more than just a measily 10k to me", and it's game over. Once that single person releases their work microsoft has paid out (no doubt numerous times) 10k for absolutely nothing.
With a bounty you don't hand it over until it works
Being able to put this down on your resume could possibly overshadow any possible lump sum that would be offered. Long term, this is possibly chump change if you factor in what it could do for you career wise long term.
Also, I wouldn't be doing this for the money and I doubt many would. You do it because you want to, it's fun, hacking on things like this is just plain enjoyable.