If they want to arrest someone for calling a politician fat

If it had been only that, this would not have happened. The BKA is a very professional police force. So there must have been way more. And this has nothing to do with her being a politician (except maybe for the reasons of the perpetrator).

And I don’t care what the laws are in Germany.

But it is the law here. This is not America. And that is good, looking at what is happening there. Which could not happen here.

They can make how many ever useless ass laws they want, doesn’t change what is morally right/wrong.

What you might think to be morally right or wrong. The world is not America. Thank goodness for that.

The first sentence of the German "Grundgesetz" (Constitution) is "Die Würde des Menschen ist unantastbar": Human dignity is inviolable. Think about it.