There is a huge discrepancy between the described motivation and the actual proposed section 126a. The proposal from January that I have here[1] only applies to a couple of explicitly enumerated potential crimes like propagation of child pornography and money forgery. Plus, the prosecution would need to prove that you created the service with the purpose of furthering these crimes. Also, the service must have some kind of access control. I do not see how a Tor exit node would fall under these criteria. A site hiding behind an onion URL would be a completely different matter.
[1] https://www.bundesrat.de/SharedDocs/drucksachen/2019/0001-01...