Is this a call for protocol enforced fees to fund development? Seems like a strange way of making the case for that.
Not at all. All Hearn is saying is that if people want professional-grade Bitcoin software, they are going to have to pay for it. I disagree to some extent because much of the most widely-used software available today is professional-grade, and yet it is open source and free. There is no reason why Bitcoin won't be similar.
"Protocol enforced fees" require a central authority to set the fees. That will never fly, especially when market-based fees will work just fine.