Are they upset because they don't bar men from wearing dresses?

Not sure why the dress code was instituted, but lots of places have dress codes and you think that'd be a bargaining issue ... not something as silly as this sounds. Besides, you'd think in this day and age when we worry about terrorism, it might be a good idea to even have uniforms that would be difficult or expensive to duplicate to reduce the chance a terrorist could "sneak" into a control tower and do any damage.