Europe has a different conception of free speech and censorship than we do.
Censorship is acceptable and desired in Europe. Germany, France, Italy, Spain, etc., all censor entire categories of speech and types of speech, including for example criticism of religion in Germany, or expressions of religion in France (to cite opposing examples). Free speech in Europe is really just what the government says is free; the default assumption being that the government has the right to censorship speech unless it is shown to warrant free speech protections.
In the U.S., freedom of speech is presumed. Censorship is only allowed by the government if the government can show that restrictions on speech are warranted, and in such case the restrictions must be limited to those necessary to address the reasons for placing the restrictions. But, censorship by private parties is allowed without restraint (accepting certain physical facilities like shopping centers) because not speaking is regarded as speech in the U.S.
So, Germany's criticism flows from their belief that the government should get to decide what gets censored, and not understanding that in the U.S., individuals and companies get to make that choice for themselves.