office employees who do not take work home with them, so they are free to swing their arms as they leave work. Implies minimal commitment to the job.
"Take your briefcase with you -- don't want to look like an armswinger these days."
An arm-swinger is someone who swings their arms widely while they walk. People who swing their arms widely while they walk are generally over-weight, and tend to walk slowly. It is likely that a wide arm-swing is needed to counter-balance their large body mass while walking.
Arm-swingers are most notable when they walk in the middle of a busy sidewalk or corridor, thus inhibiting the ability of faster, non-arm swinging pedestrians to pass them. This can lead to great frustration and general deriding of fat people when one is in a hurry.
I would have just made my train today, but I got stuck behind a fucking arm-swinger when I was walking to the station.
A short obese women who is so fat that she must swing her arms while walking.
That armswinger just nailed me in the dick when she walked by.