Dealing with bots is hard, banning downvotes is easy. Ideally, with infinite resources, the bots would be eliminated.

In the very best case, this would force him to write one half-decent post per sockpuppet.

that's actually a huge inconvenience for him - writing a good post, using the puppet to mass downvote, then an hour later the puppet is caught because it is mass downvoting and the votes are reverted.

Limits per sockpuppet = more sockpuppets

presumably there is a cost per puppet. Combining this with my above suggestion would mean more articles for him to write...