He attended the March on Washington in 1963. Maybe it’s not a big deal, but it’s accurate. And people bring it up for exactly the reason you are saying, ie to demonstrate that he has been consistent over his entire life, so you don’t have to be a pedant and “well actually” over it. Kinda makes you look like a jackass. Also, activism and campaigning should be normal, like you say, but the fact of the matter is that it’s not and people putting in as much work as they’ve been putting in is extraordinary.