Those vests do not have infinite life spans, they get taken out of service based upon years in use or exposure to moisture (sweating). It’s almost certain that this vest was beyond the manufacturers recommended service life, thus giving them some additional protection against reckless lawsuits.
Apparently,the shooter MOL missed the vest. Wound was "over the vest." Perhaps not worn properly, etc. etc. Also, beyond "small caliber" we don't know the details of the weapon.
Quite accurate to state:
Those vests do not have infinite life spans, they get taken out of service based upon years in use or exposure to moisture (sweating). It’s almost certain that this vest was beyond the manufacturers recommended service life, thus giving them some additional protection against reckless lawsuits.