From a retired Army officer:

Jonah, We spent Labor Day in Columbus, Georgia, right outside the gates of Fort Benning. Soldiers on pass were all over the place, and I was reminded at how great a holiday Labor Day is for the military — it is a true day off for guys in uniform. No parades, no ceremonies, no memorials, no speeches, no official activities, no feeling sorry for yourself (your first Thanksgiving away from your family is sad; you first labor Day away is “So what?”). Labor Day is really the only day off the military can really count on.

Translation: Labor Day is great for the military because it is so meaningless.