Curation hunting bots which use historic voting pattern data are content agnostic

I would say not entirely, although I am mostly agreeing with you that they amplify or perhaps just accelerate existing patterns. To the extent that the votes they are looking to predict are content agnostic, they are too, but to the extent the votes they are looking to predict are not content agnostic then the curation hunting bots aren't either.

Example:

1. Author X consistently gets high rewards due to valuable content
2. Author X consistently gets high rewards due to close-to-break-even purchased votes.

These are very different IMO and likewise whether curation bots are hunting #1 or #2 is also very different.

#1, I would view as doing a service two ways:

1. Curation hunting bots and competition between them returns more curation rewards to the pool
2. Since it surfaces the content faster, people can then use rewards as a real time and trusted content discovery method (trustworthy because there are real resources betting on it).

If free downvotes work, there may not be much if any amplification (rather vote acceleration, as I noted above), because if the content ends up overrewarded in toto (curation bots plus later votes), it may attract some downvotes. We'll have to see if that actually happens though.