Bittrex only gives 14 days to remove any funds before they shut down the wallet.
Stating the obvious? When it was delisted i instantaneously made a request to withdraw my funds. This is not a one-off, hundreds of people have had their withdrawal requests ignored and coins taken, when requested within the 14 days.
Regardless, think rationally, there is no need to have a time window on withdrawals. This is just a trap. Other exchanges let you withdraw delisted coins at any point after delisting.