Perhaps, because a stall horn isn't present when the Capt. comes in, and the two pilots are not rightly afraid of its meaning. They do not speak the stall language, they are flying an airplane that can do anything they think to help, and other things.
Perhaps when Strall goes, a packet of smelly cat poop ex[plodes in the cockpit, so no ojne can not know their danger of dying. Stall is the language you will all be soon dead, nothing else matters but to re3sume flying. Unles you have this deathwish.
Hard to ignore, this Stall warn, and there is not such thing 'spulios'.