Although the article doesn’t mention it, I think there also exist exemptions for certain special forces units that need to operate under-cover.
You are right small teams have always been allowed to grow not only facial hair but long head hair as well. Nothing sticks out more in the ‘stans than high and tight clean shaven white guys. Same for Latin America. The brits have long allowed facial hair for certain regiments. Having to keep the pedostach is a relic of the cold war when you needed to seal a M40 mask in the event of a chemical weapons attack. Now the agents are so lethal a pin head sizes droplet on your skin is fatal and getting into MOP4 before you die is not a sure fire bet anymore.