Newspapers report facts in one section and editorial opinions in a different section. They are clearly compartmentalized from each other. They are both useful. The editorial staff has a long history of making presidential endorsements. We’re free to disagree with the endorsement, they are not telling us what to think, just giving us a perspective to consider among all the others we hear.
What the Post did is highly abnormal. It’s not like the editorial staff decided out of nowhere to write up this endorsement. They did because it’s an automatic thing they’re expected to do before elections.
Think about watching a sports broadcast. There’s typically two guys, one reporting play by play (facts) and the other adding color/analysis.
I think they’re implying that it can be rude to broadcast someone’s age, since some people like to be private about it.