I agree with NickB, the explanations are absolutely reasonable. My question is though: What is the recognition of this legislation worldwide? I reckon, within the EU a consumer could now fight KLM based on this Austrian decision.
I wonder why there's no fixed place of jurisdiction with Flying Blue. In contrary, in the §1.2 of the T&C's they mention the possibility of country-specific alterations. To my understanding, this gives Flying Blue the possibility of changing the program for every country individually.
So it looks like, that an Austrian member may keep his/her miles for up to 30 years while a French member looses his/her miles after 20 months.