Its not just the govt employees, its almost all metro riders. Coming down, someone blocking an escalator can be the difference between making a train or not, which adds 4-6 minutes of unnecessary commute during rush hour. Coming up, some people are trying to connect to a bus or another line. Its just plain courtesy to your fellow riders.

I ride the metro from Union Station fairly regularly, including today, and I can tell you that the escalators are plenty wide to ride down with it in front of you (or behind you) and still allow a reasonably girthed passenger to pass by.