Which seems like the best solution - early votes by others (not the author) should still increase the % of total post payout that goes to author

Then bot votes and dummy account votes would still count and the change would be essentially meaningless.

I still strongly disagree with your proposal to just return all of it to the curation reward pool of the post in question, as that would incentivize other users to vote on posting that has large self votes

That's not my actual proposal, by the way, it's just one of several simplified methods that would serve better than what they've implemented. Mine is here, and avoids that problem.