The "gambit" is offering $70,000 worth of grants with the ultimate goal being, hopefully, to recruit the graduates.
If I'm understanding correctly, the people that would go to Hacker School aren't necessarily ready for a job at Etsy (the goal being "turn people with a passion for programming into professional engineers").
So it could fail in several ways and the money would go to waste (at least from the perspective of hiring). Now, I would imagine $70,000 isn't much to a company like Etsy, but "gambit" is still an appropriate way to put it.
I used to work for Marc and I think he's an excellent recruiter. You could read this article as a tactical way to increase diversity or just as a tactical way to put yourself on candidates radar. Etsy has been making incredible hires across the board since he joined.
It's more of a good thing and an achievement rather than a gambit.