Just a hypothesis: that professor would have abused you as a working slave. And he knew that no person in his right mind with significant work experience and “above minimum pay” could be Ok with it.

I suspect it had nothing to do with your qualifications - rather he probably wanted to avoid saying “sorry, but I wont be able to abuse you enough”.

At no institution in Germany have I head of “if you don’t publish in a year, you are out”. Usually you work 2 years as a slave with no context what your research is and after the first couple of years, you are allowed “to think loudly about a topic”.

This encounter is not “normal”... Keep looking. And yes: Academia knows that industry works on hard shit. And they often don’t want “outsiders to take a look under the rug”... They create a fake world to justify themselves more often than not...