This definitely seems like a reasonable solution. I am curious if there are other options though. Given @decentralion 's comments on the Community Call yesterday my idea may be rejected entirely as it certainly looks like “shareholder capitalism,” but what about opening Grain up to be bought by other parties?
The main issue I see with this counter-proposal is that there could still very well be a redemption problem if those new buyers are not intending to hold their Grain. However, with the idea for Boosting being so exciting, opening up the selling of Grain could very well encourage those with extra cash to secure some more Grain, with the prospect of using it at a future date to support ideas within the space.
Either way, switching from “peeling” Grain to minting it seems pretty wise for project use. I just know I would definitely be interested in swapping some DAI for Grain since I spend most of my time at Maker. Thus my earning potential for Grain is pretty capped, even though I really love and support the project. I imagine there are more like me out there, and such an arrangement might offer my security for funding SourceCred in the future.