You illustrate the point well and maybe I'm just not well versed enough in the topic. You imply that a charity warps the free market by undercutting profit-motivated competitors but in the last statement you give the vendors the freedom of choice in regards to their customers. Is there any reason why this same freedom of choice can't be extended to people who choose a specific social outcome at the cost of less (or nil) profit? For example, are B-Corps fundamentally less "free market"? Or does the very nature of free market imply a profit maximizing function? As an example that comes to mind, I'm curious how not-for-profit and for-profit hospitals interact in a "free market" of healthcare in the United States.