Another consideration is, would this vote negation even have any noticeable effect, or would it just add overall negativity to the platform!
For a simplified example, lets say that Bob and Alice are the only two voting, and as described they have roughly equal stake. Alice votes on chickens and Bob votes on what he deems worthy. The rewards pool will be split 50/50 between the two topics. Now if Bob sacrifices some of his power to block Alice... it's a wash. He cuts her power by 50%, cutting his own by 50% in the process. Now when they vote again the next day... the pool is still split 50/50.
I don't see how vote negation does anything more than the simple strategy of voting on what you like... and not voting on what you don't.