About BCC, the logical thing for Poloniex to do would be to credit accounts according to the BTC balance on August 1st 12:20PM.
According to section 18 of their updated TOS :
"18. OWNERSHIP OF TOKENS
You hereby certify to us that any Tokens used by you in connection with the Platform are either owned by you or that you are validly authorized to carry out transactions using such Tokens, and that all transactions initiated with your Account are for your own Account and not on behalf of any other person or entity."
So yeah they should credit BTC holders on their exchange for their rightfully owned BCC, even if they do not offer it as a trading pair.