They made changes in the 2nd printing to match the overall direction of that faq entry. Every class raises their unarmed proficiency to keep up with their weapon proficiency (which was missing in the first printing).
In the fighter case the change notes that the proficiency for unarmed attacks depends on their weapon group, like it does for simple, martial, and advanced weapons.
Compare:
Fighter Weapon Mastery, 1st printing wrote:
Choose one weapon group. Your proficiency rank increases to master with the simple and martial weapons in that group, and to expert with the advanced weapons in that group.
Fighter Weapon Mastery, 2nd printing wrote:
Your proficiency rank increases to master with the simple weapons, martial weapons, and unarmed attacks in that group, and to expert with the advanced weapons in that group.
Weapon Legend, 1st printing wrote:
Your proficiency ranks for simple and martial weapons increase to master. Your proficiency rank for advanced weapons increases to expert.
You can select one weapon group and increase your proficiency ranks to legendary for all simple and martial weapons in that weapon group, and to master for all advanced weapons in that weapon group.
Weapon Legend, 2nd printing wrote:
Your proficiency ranks for simple weapons, martial weapons, and unarmed attacks increase to master. Your proficiency rank for advanced weapons increases to expert.
You can select one weapon group and increase your proficiency ranks to legendary for all simple weapons, martial weapons, and unarmed attacks in that weapon group, and to master for all advanced weapons in that weapon group.
Versatile Legend, 1st printing wrote:
Your proficiency ranks for simple weapons, martial weapons, and unarmed attacks increase to legendary, and your proficiency rank for advanced weapons increases to master.
Versatile Legend, 2nd printing wrote:
Your proficiency ranks for simple weapons, martial weapons, and unarmed attacks increase to legendary, and your proficiency rank for advanced weapons increases to master.
Progression for unarmed attack proficiency has been added at every step, but always gated behind the weapon group selection. The original FAQ was just a quick fix until they got this done.
And yes the first printing granted legendary proficiency with unarmed at 19 after no other progression, I just noticed that.