I totally think there are/will be possible solutions to modify such incentive-based economies to prevent people taking financial advantages while not contributing to the system..
I myself sometimes deeply think about similar policies and ideas to change the effects like downvoting, flagging and self-voting...or even having different accounts at once and intra-upvote eachone...they're not good for the health of the system..and if they're not controlled, they may cause unreliability of the network..

I didn't really understand your idea how you wanted to prevent haejin to do self-voting anyway..