True, trust are not specifically mentioned but they haven't been excluded either and the ATF legal staff has determined that the trust is an entity similar to corporations. In fact, a trust is a little more controlling than an corporation because you're limited to yourself or you and a spouse as an A/B trust; whereas, under a corporation, any listed corporate officers in the company charter (including the janitor if listed) are able to take possession of the item.
Could they change their mind, sure thing they have done it in the pass on a number of issues but it might be an up-hill battle to revoke current stamps given all the approvals. If anything, they may just slam the door shut on future transfers.
It is also true that if you can get a CLEO sign-off that is the way to go, if anything to prevent the nay-sayer's but unfortunately too many CLEO's are trying to force their own political policy on people as opposed to providing a service and finding out what's in their backyard. This was probably at the heart of why TN passed a bill requiring CLEO's to sign-off on Form 4's.