Seems like Poloniex indeed have access to their wallet. https://steemit.com/poloniex/@sc-steemit/poloniex-still-has-access-to-their-cold-wallet-get-your-assets-while-you-can
Sending you some POLOLOSTKEYS just for the funcies of it. You didn't really need them to do the proposal transaction though, and you can still do it to see what they do :)
Good news! I'm rich! Haha. Anyways, my BitShares2-light wallet (v2.0.170522) kept producing an error trying to broadcast the proposal so I was never able to send one out.