No, not liking some one's opinion is not valid reason for excluding them. You are supposed to include and exclude people based on whether you think their use of the trust system is valid or not.
If you don't trust someone's judgement you can surely exclude them without waiting for them to start [ab]using the trust system.
There was also this lunatic DT1 member who claimed to be including people based on whom they argue with, I wonder how that squares with your valid reasons.