Upon re-reading the bit about the Hork-Bajir having their forest reserve, my first thought was: "Well, I bet that cut down on illegal logging."

My brain is weird sometimes...

I'd be willing to bet that some nothlit Yeerks took up positions that were helpful to humans, though. (E.g. search-and-rescue for hikers, feral dog control in Moscow, border patrols, rabbit hunting in Australia, etc.) That would make humans a bit more favourable towards Yeerks in general.