My 884 bitcoins are in limbo and I'm scared
You effing idiot. What are you doing putting so much BTC into a wallet you don't have full control over.
Well he could of just mined ETH for the last 1.5 year to that address and just sold for BTC.
That doesn't matter... As long as he continued mining Eth to a poloniex wallet, having 884 BTC accumulate on poloniex without taking some out is the stupidest thing I've read in a while... for multiple reasons:
1) He doesn't have control of the keys: All you have is a password protected "account" there and are at the will of poloniex.
2) Even with going through all of the verification processes on poloniex, the max you are able to withdraw per day is $10K in Bitcoin... Obviously you can see where the problems come into play when you have ~900 tokens that represent $2.5K+ per token. Without verifications, it's $2K per day which is even more problematic
3) It's stupid to keep that much wealth in one wallet regardless... multiple cold wallets, hot wallets, etc. should be considered. And for god sakes, no web wallets.