It's a disgrace but it helps to have some context; a veteran force in your society is a destabalising thing in and of itself.

The USA's acceptance of bearing arms, tolerance of militias (who we've seen are hard to control and prone to war crimes in East Timor, parts of Africa, Iraq and possibly now in Iran) and failure to break up groups calling openly for a race war leaves a lot of places for veterans to go and feel comfortable in a military context.

If you'll forgive me for using wikipedia, we see that Washington will still have memories of

dangerous times when veterans were a domestic army looking for a leader.

Putting them on a watch list is simply rational behaviour. The real outrage is that they were treated so poorly in the training and the war itself that we can anticipate resentment upon return.