Is the shelf life actually relevant?
I know very little of stingers, but would guess that the battery life does not extend to twenty five years (but could be replaced, so negating shelf life?).
I also have no idea if an unmodified stinger would fire at a U.S. aircraft, in a similar way that the ex soviet AAA guns would not track soviet aircraft, due to their IFF system saying they were friends.
I could be wrong on all this, but do find a shelf life of twenty five years a bit excessive.