I would just bet most of those non essential personnel are RATS. Too bad if they all lost their jobs.
Under their union contracts, they will (unfortunately) all get paid eventually. However, if their jobs are non essential or actually destructive, it doesn't follow that it is more of a loss to taxpayers than if they were doing their jobs.
If the entire EPA staff stays home and is drunk or high, at least they can't cause any mischief like Gold King Mine disasters.
95% of the political donations from the Federal workforce went to Hillary in 2016.
Let them eat ramen!