The German basic law protects people's personal honour (article 5, freedom of expression), and this goes back hundreds of years. (strafrechtlicher Ehrschutz).
>"These rights shall find their limits in the provisions of general laws, in provisions for the protection of young persons and in the right to personal honour."
This is reflected in the German criminal code Beleidigung(Insult), unchanged for about 150 years.
>"The penalty for insult is imprisonment for a term not exceeding one year or a fine and, if the insult is committed by means of an assault, imprisonment for a term not exceeding two years or a fine."
This extends to everyone, not just politicians. For example, flipping someone off is not legal, and you'll be fined if someone were to take legal action. The headline of the article and the general tone of is misleading.