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Guard him from taking unfair advantage. Shout and resist if necessary. If you continue to hive. Isn't it the spirit of decentralization that hive emphasized so much?

Blocktrades holds about 5M. Assuming he has a few hidden accounts, let's say 10.
The current top witnesses are voted with 60-80M of stake.
So yes, he has a big voice, as he should with a big investment. But he can't dictate anything, and I don't even see him trying.