Fantasic example, exactly the type of alternative structures that could make sense in artificial markets. I didn't know about this.
One bit I'd nitpick is restricting the mission to non profit. Profits could still be good, if shareholders have the right to decide what to do with them. Non profit structures force you into spending "above the line" which muddles things by design. Having a profit is a useful health check, and profits can be spent in a more transparent way.
Imagine such a structure owning street level retail real estate, a busy shopping street. Renting at market value to H&M produces more "profit" than renting at reduced prices (or free) to a community op shop. There's a trade-off that the "owners" might make, if they would like to buy more real estate or whatnot.