SEC has made an anouncement to crack down on exchanges and attempt a full on crash of no recovery with Bitcoin. I think they are just butthurt.
They can't really find an institution or body to talk to about this because everything is decentralized (hahahahaha) so they see harassing exchanges as their only option.
I can understand what they are trying to do. SEC don't want another Mt. Gox incident again which is very frightening if you think about it. Millions of dollars worth of coins being hacked have an impact not only to the users of that exchange but also to the integrity of cryptocurrencies as a whole.