If I'm reading this right, the last estimate ($5.5 billion valuation for Reddit) is from May 31, right before the revolts.
Either way this doesn't surprise me at all. Contrariwise to what Steve "greedy pigboy" Huffman might believe, investors aren't stupid; they know that the main asset of a social media site like Reddit is its userbase, and that if you piss off the most contributive users there, the value goes down considerably.