The proposal isn't really about buying or selling DEC, that part is mainly to ensure the pool is at a reasonable level to add liquidity. If you add 200k of USDC liquidity below range, it actually holds to the DEC price down. This whole proposal is essentially in response to an error in cryptoeater's previous proposal where the v3 range was set incorrectly and there is no liquidity below the 0.00083 - .001 range. This can help stabilize the price because there is currently a cliff the pool falls off after DEC drops below the range the DAO added liquidity at.
It is the company's job to build a better game, not the DAO. Matt seems to be willing to take game related proposals into consideration, so feel free to make some if you like. Let me know if you need help.