It blew my mind when I learned about that. It's not even a real tradition, it's a part of the military industrial complex.
It's just marketing bullshit, but folks will defend it.
I posted the rules of the flag that someone linked to earlier in this thread on a FB argument feed and it always ends with someone saying "I served XX years and kneeling disrespects my time served and those that died." Thanks for your service, but no it doesn't. You fought for the freedom of the individual to kneel.
We have angry people calling those kneeling "snowflakes" or "babies" but they are the ones whining about a flag and a person doing a peaceful protest.