Screening is hardly what I'd call a relatively low-paid job. Federal pay, benefits, education, growth and transfer possibilities take this job way above housekeeping or fast food.

They have an important job and they are informed when they take the job that one of the 'conditions' of a critical national security job is that you can not strike, you can not leave the public at risk. Don't like it, go find a non-essential, non-national security-related job. There are many of them. This is not the first time we've had a shutdown and sadly, it probably won't be the last.