Topbunk is absolutely right. Consider in any emergency evacuation, you will have broken bones and a few serious injuries. If the situation is you have got on the ground safely, what next? It is correct to pause for a moment and try and find out what is going on in the cabin or externally before blowing the whistle, even with a fire warning going. I always get confirmation of visible smoke/flames or serious damage before blowing the whistle and initiating the evacuation. I see no need to get an evacuation going on possibly a false warning. Remember, the crew know that if a situation is catastrophic or uncontrollable, they are permitted the initiative to commence evacuation themselves without waiting for the order from the Captain. To have passengers hospitalised on a false warning to me smacks of being over-hasty.
419, you are, and the Captain has signed for it.