Of course if you take up a personal interest, sure you could become invested in politics as you could with any other topic or fascination. But this person in the post is clearly shown to not have any sort of curiosity or interest in that way. Taking up an interest in politics isn't the same as with sport or art, it's something that shapes your day to day life at all times.
The way I see it, interest in politics is similar to interest in one's personal health. Most people don't take a very active interest in it, happy to not think about it so long as there isn't any trouble, while others find it gratifying to do so, and take a more proactive action in learning, improving and teaching others about it.
But for that large number who don't care, they won't want to alter their lifestyle to take up the advice of others who know better. All that is until suddenly they're met with the result of their inaction and inattention, which is when they are easiest to convince.
They reserve the right to make fun of German, as does everyone else who got to shoot at Nazis in 45.