"They can "dictate monetary policy, which is normally the function of a central bank or a government", he said."
I do not think so. The monetary policy is determined by the algorithm already.
True. Monetary policy is set by controlling the money supply or changing interest rates. The rate of increase in money supply is pretty much set in stone, by the algorithm.
Why do people confuse the price with monetary policy? Whales may be able to influence the market, but this will decrease with time.