It's a frustrating situation, I agree. Panicked crowds are not fun, and they're dangerous.
You ask a good question about the "in" versus the "out" doors. A good way to envision things is that, yes, a character could certainly exit through the "in" door. The problem Cyril faces is that the customers in the store have split themselves into two groups, half at the "out" door (by the cash registers), and half at the "in" door (by the customer service desk). The crowd and the limited egress combine to form a trap, if you will. Of course, another way to think of a trap is to decide it's a puzzle and to come up with a make-shift solution to the puzzle. Your idea of hiding until the crowd is past is a good one. So is climbing to higher ground. So is retreating away from the crowd. I'm sure there are others that I haven't thought of.