Because at the end of the day, it's all well and good to have the gun on you. It's even better to get the trigger time and put lead down range and be able to hit gongs on demand with razor sharp speed and accuracy. But if you don't have your mind right when it's time to slay the dragon, that gun is nothing more than extra weight on your belt that doesn't do you or anyone else any good.
You really should read his entire post which has a lot of practical experience. And you should read the comments which are a good - if dismaying - view into the Reindeer Games being played with police forces by Woke politicians.