Pheace: He did? I missed that part, my bad.
Still, they are supplying the game, digitally to Germans, updates and all. If you are in Germany at the time that happens, and with no way to ascertain the difference in age, I can still see how it might be a case of 'just on the safe side'.
The time of supply for the purposes of law is deemed to be the time of purchase. In my case, at the time I bought the disc from the store. Because the service is bound to my account details, it is then my responsibility to ensure that no minor has access to this game through my account.
You do bring up a valid point in stating that Valve is wildly inconsistent in observing German law though. Formal age checks are indeed required for 18-rated games, which Steam doesn't observe, even though practically every other German retailer does.
Gamersgate and GOG are just as guilty of this though. Origin and UPlay comply with this law in another way, but in a way that is quite frankly bizarre.
Edit: In other news, Sleeping Dogs (EU) has reappeared in my account history list, but I'm too tired to check the game now. Sounds like the Russian version problem was related to it though.