Presumably to try and reduce the chance of a mass panic among their users.
9 times out of 10 when an exchange or broker is "hacked" its been the operators of the exchange.
What do they care if there's a panic? They have "paused the sidechain". No one can act on their panic.
9 times out of 10 when an exchange or broker is "hacked" its been the operators of the exchange.