A perfectly rational agent should choose behavior that works when other agents apply the same behavior.

If everyone uses her strategy, the queue can only get shorter if there's exactly one person left in the queue, but it gets longer each time someone joins it.

In an idealized world where everyone can instantly teleport, this doesn't technically reduce the throughput of the queue, however it does still increase its size unnecessarily. (and in the real world it also decreases throughput, potentially by a significant amount if the queue is physically long enough)
 

Even granting that she doesn't care about anyone else, the strategy is still slower for her even if she's the only one using it.

Judging from the picture, she will lose at least a few seconds when the person in front of her leaves the queue and she still has to walk the remaining distance to the front of the queue.

For a more extreme example, imagine the queue is a kilometer long. Assuming everyone before her shuffled along like the average queue enjoyer, she would now be one person-width away from the goal had she shuffled along with them.
If she used her "perfectly rational" strategy instead, she would now have to walk a full kilometer which, being very generous to her, would cost her an additional 12 minutes.

Perfectly rational behavior, if your only objective is to annoy others.
 

(there is perhaps an argument in favor of some variant of her strategy, if there is a high time/effort/opportunity cost associated with starting and/or stopping, but I think realistically this will rarely if ever be the case in an airport security queue)