poloniex is an exchange. They aren't on any block. You deposit coins, trade them, hopefully withdraw them. The coins are what may be worthless...if they aren't on the valid fork. If you deposited before this happened they should be fine, Snailbrain rapidly warned the exchanges to avoid problems when this came to light so it shouldn't be a problem.

Any HUC  in an exchange before the forks, they should be normal.
Ditto any you already had in your wallet.

I decided to leave it until it's fixed properly, if you're the kind of person who likes to build up large quantities of imaginary coins and then will be pissed off to find they are no good...maybe best to do the same Ditto if too much arsing about downloading and updating doesn't suit you. Just wait and save yourself the grief

Interesting to me is the chat on that exchange, right now during this problem and trading being stopped, there's a lot of confidence and enthusiasm for HUC. That's a new one on me, usually it's the opposite. So once things work out and all is as it should be you can probably expect a decent rise in value.