Interesting worse case scenarios. I believe the second one would be very hard to accomplish as well. There are close to 200 million STEEM vested and only a little over 112 million liquid, of which about 80m on exchanges. To gather enough SP to become a 'dictator', one would have to convince many stakeholders to power down and sell their stakes. And it wouldn't happen overnight, there would be a counter-reaction, which doesn't have to be a bid for stake.