you're saying that anyone else who votes within that 15 minute period could have at least portions of the curation reward end up back in the reward pool and distributed to the posts with higher rewards, too

Yes, that's how it works. All of the early-voting curation rewards that now go to the author would go to the pool instead. (If you think about it, just trashing the self-vote rewards doesn't help because you can always use a bot vote or a dummy account instead.)

Regardless, it seems to me that this could be more readily solved if instead of returning to the reward pool, the allocation went to curation for that particular post.

That would definitely be a better solution. A big self-vote at the beginning would be an incentive for more people to vote on the post, which I suppose might be an issue, but it would be an improvement over the proposed method and might be an improvement over the current method.