There’s really only two likely scenarios:
They are jihadists who have gone off the reservation to join up with a domestic terrorist cell.
OR:
Like any Afghan with a brain brought from that miserable hellhole to the United States of America, they took one look at Cape Cod and decided to abandon their commissions and go absent without leave rather than return home to fight the Taliban only to be abandoned by Obama at some point in the future.
My bet is that if they are not caught, at least one of them will be selling real estate someplace down the eastern seaboard within two years, and the others will open up a kebab stand down in some hipster part of Boston or NYC.
They haven't left a hellhole, they have left a shithole....maybe they won't make it back on Monday!
You could be right. OR they went to a strip club and lost track of time. :-)