It's one thing to say that a munition of a certain type under certain conditions has a shelf life of X before it is no longer reliable for it's intended purpose.
It's another to say that
a) the chemicals in those munitions are no longer dangerous after the shelf life expires (false)
b) chemical weapons materials in uncertain configurations under uncertain conditions have the same shelf life of X (false)
cosmo20002 makes the mistake of extrapolating from a statement that may contain some truth in narrow circumstances to a sweeping generality that's more untrue than true.
“The American people are tired of liars and people who pretend to be something they’re not.” - Hillary Clinton