You think people running an exchange go to bed while BTC is forking? ... really? .... like seriously?
I think you'll find that most admins at exchanges are starting to forget what their wives and children look like.

Us and every other exchange could have split the coins, added markets and unpaused everything in 5 minutes if we wanted to. Our scripts to do this were written well in advance. The reason exchanges allowed trading but kept deposits and withdraws disabled is because we could guarantee that BCH/BTC in the system after the doors closed would be 1:1, but the exchanges couldn't actually split the coins, start moving them around to avoid attacks until BCH was actually producing blocks - thats why the doors (deposits/withdraws) stayed closed at all exchanges for quite a while after.

Did you expect us as an exchange to go "oh well, it's only 100% of our collective customer funds at risk, what could go wrong, yolo"?