Those things are made more with terrorism in mind
Acutally it was more about copyright protection and illiegal downloads - when it comes to terrorism there are even more ****ed-up measures in place
I sincerely doubt they would have considered Deutsch Telekom liable because a bunch of terrorists discussed their plans on the phone.
ISP's were exempt form liability (as are Phone Providers and Post Services, in similar instances)
but how are they going to arrest you for complaining about minorities if it's all free and open
It is still possible to identify a device by it's hardware IDs, something the makers of the original law where unaware off
EDIT: Just to add more context why this is a big deal:
WiFi has not been a thing in Germany has had a huge impact on the telecommunication market, esspecially concerning cellphone services. It is one of the main reasons why german cell-service providers get away with some the weird and ****ty service models they have been pushing, esspecially in regards to mobile internet access.
Those will not change overnight (esspecially considering what's happening in other segments of the telecommunications market) but here is a start.