To me, it’s more about the goal he was trying to achieve. He clearly did it to taunt and insult. In that context, I can see how this should be a punishable offense (not death though).
It would be a similar thing if you had learned that the prime minister of Sweden likes to create art at home. Then buying one of his art pieces and burn it in front of his house. Sure, burning art is not a punishable offense, but the goal of intimidating someone with such a symbol could/should be.
I agree with your first two sentences, but not with your last one. You have to take into consideration that many people are in different situations. If you have trouble making ends meet, if you need your job to feed your family, you might not be inclined to risk your job to protest. What I’m trying to say is, not all people that don’t protest are Nazis. Stating they are creates another layer of polarization that isn’t bringing us anywhere near a solution. And yes: Us. even though I’m not a US citizen, it unfortunately affects the world.