Can i trust poloniex?
No you can't
The exchange already has some issues, now like the one this user raise not so long ago:
Poloniex Has Not Added 3 Deposits to My Account for 3 Monthsi have some funds there, and my account is frozen, they are asking to download the app be able to use funds, wich is very weird, should i contact a lawyer instead?
This should be a wake up call, please move all your funds out of that exchange once you are able to access and unfreeze your accout
"Not your keys, Not your coins"