How about this:
It is illegal for a person (call him Fred) to drink while driving, but nobody would argue that giving Fred (who is over 21) sealed beer to take home with him with the intent of him drinking them later, and then Fred choosing to drink the beer while in the car on the way makes you liable.
It's almost a perfect analogy of the original scenario, and it shows how this DOES in fact, strip the actual person responsible of their moral responsibility.
Except this isn't a perfect analogy.
The judge ruled:
that a person sending text messages has a duty not to text someone who is driving if the texter knows, or has special reason to know, the recipient will view the text while driving.
The key is "if the texter knows, or has special reason to know, the recipient will view the text while driving." As in, you know or have reason to know that you are putting the recipient at risk.
So the perfect analogy would be as you describe only if you add the knowledge that the gifting person knows Fred has a history of drinking and driving and knows that he will do so with the beer you've provided, or that Fred mentioned he will drink it as he's driving.
Knowledge that the risk is (or almost certainly is) increased is key. This does go hand in hand with reducing the responsibility for a given party to less than 100%, but it is not the completely stripping it that you have stated.