It's hard for socialists to comprehend asset markets...or economics in general. Whoever these people are, they have no clue about anything market-related. The entire scenario that they painted, from the very start, is nothing but a BS attempt to gain power from the uneducated/uninformed, which is nothing new for people who have adopted this type of "progressive" politics/philosophy.
Even if we were to assume that a hedge fund would want to buy "all of the STEEM," they don't factor in how much STEEM is locked up in SP, as you mentioned, which is somewhere around 75% right now. So, best-case scenario, the hedge fund could only hold a maximum of 25% of all tokens.
If a hedge fund bought $100 million of STEEM at current prices (even if we assumed that the price wouldn't rise while they were buying, which would be stupid and incorrect), and the price then increased to $700 million, why would they then proceed to tank their $616 million profit rather than cash it out or reinvest it in the ecosystem or elsewhere? They would need to be "farming" accounts and posting for a very long time in order to see any returns that are comparable to that increase from prices rising. And the system would be dead long before they could take advantage of it...and they'd lose their massive profit.
My suggestion for them would be to actually learn about the blockchain, economics, and some basic math, perhaps.