Bittrex doesn't want to make wrong choice due to some funny guy sending the confiscated coins to them... They would be liable for the losses if they make the wrong choice...

Like other exchanges, they planned to wait for some development group to revert the changes in HF23 and 23.1 and restore the confiscated amounts to original wallets, but I don't see that happening as most of those people have already switched over to HIVE instead.