Some news is quite miss leading saying captain ordered not to evacuate.
The reality is captain used 90 seconds to evaluate the situation and decided to proceed with evacuation.
Some evacuation is decided in the air such as partial gear landing, even for that, captain needs to assess the situation on the ground before ordering evacuation.
But for this case, flight crew only knew it was a landing went wrong. Taking time to assess what the situation is like shows professionalism. If the cabin is in immanent danger such as fire or smoke (which has no indication in flight deck) cabin crew can initiate evac with out PICs permission.
There are several steps needs to be done before ordering an evac. For instance, pilot needs to make sure engines are shutdown, with engine separated there is likely to be no engine indication on the instruments, hence can not confirm if it is still running, pilot can not see what is on (or not) the wings and needs to relay on outside reference.
90 seconds to evacuate the aircraft with half doors open is for aircraft certification purpose NOT a time limit for pilot to assess situation to make a decision.
It is sometimes safer to stay in the aircraft than wonder around on the tarmac.