This isn't really an ideal article to kick off a series of debates that could be very interesting. It's trying to relate too many concepts from taxation theory to economic stimulation to labor management, etc, etc. If the main point is to ask if capital or labor risks more the answer is trivial: capital. There is a -100% downside for investment and minimum positive earnings for labor. On the other hand capital has an…
As for optimizing opportunity between labor and capital, I tend to suspect that this metric would favor more equitable wealth distribution so as to maximize the feasibility of bootstrapping (low overhead, perverse incentives avoided, nothing remotely exploitative about it on either end of the deal) and to maximize the "surface contact" between capital and labor. But nobody is looking to maximize opportunity in general, only their individual opportunity, and the Nash equilibrium for that process lies in exactly the same place as the Nash equilibrium for wealth.