Poloniex did also some other suprising decisions regding ETC and Loans, I described here:
https://steemit.com/etherium/@rnevet/the-eth-harkfork-poloniex-etc-ethereum-classic-token-and-what-i-m-missing
TLDR for people loaning ETH they credited the ETC to the borrower.
Thanks. I suspect a lot of people are not aware of this and may not find out until their loans terminate.