Earlier quoted context omitted.
Couldn't you work 6 hours "for the man", and then work on a project of your own choosing, for whatever reason you wanted? (a side project, the next unicorn, some spare cash, something OSS, something for charity, or just because)
It's exactly what I do, but I suspect that the spirit of this 6 hour initiative isn't necessarily in line with what you're alluding to but rather the idea that working less hours is better for all of us. Correct me if I'm wrong about this.
In Norway at least, it's true that lots of people finish work relatively early - but only because they start work really early (6-7am)!