As was mentioned by another, a CR7 has a 29 min turn time. That means, if the inbound was late arriving (under 29 min from the scheduled dptr) the boarding begins at t-14.5 min at the latest (earlier if possible.) At ORD, the crew gets 2 min (that's right, only 2) to start boarding from the time the last passenger is off, or if in a change of crew, 2 min from the time they step on the plane. I am guessing the same policy exists for SFO as ORD.

Not a lot of time for good communications, but it keeps planes on schedule and costs down. Clearly, communications were weak given the short turn of the aircraft, but I doubt the whole scenerio was an elaboratly concocted scheme to get 1 employee in F, anymore than I believe that there is a secret base in the desert where we are covering up an alien landing, or that the moon landing was filmed on earth.