Everyone could file a complaint with the SEC as suggested from here:

https://busy.org/poloniex/@bayareacoins/every-steem-user-should-file-a-sec-complaint-against-poloniex-it-only-takes-about-5-minutes-and-these-bastards-deserve-it


https://www.sec.gov/complaint/tipscomplaint.shtml

https://denebleo.sec.gov/TCRExternal/index.xhtml

Could send this news of Poloniex's sceheme to cryptocurrency news websites i.e.

 https://www.coindesk.com/
 https://news.bitcoin.com