You'll have to explain why. It seems to me my theory fits the details just as well and isn't prone to catastrophic failure given a slightly more diligent DD. Even if it is the ring, he still precommits to going back in time to do the swap, just in case DD does turn out to be sufficiently diligent.

There's no way he burns all the time turner uses for the day at once unless there's no other possiblity. He learned in Azkaban that you always leave yourself wiggle room. And entirely aside from that, it's good for 6 uses per day. It's a new day.