I don’t know the details of the legal issues that come from setting up $ARB to give dividends to holders… from what little I do know tho it sounds like a bad idea.
A better mechanism might be to use the ETH to buy ARB (via auction or via a dex) and either burn it or give the ARB to the DAO, it would probably bring more profit to the token holders and maybe would be easier for the lawyer types to agree to.