Doubletalk indeed and I'm not happy about that court ruling. I'm pretty darn sure that line about the "certified letters" is not true. Can you write him back and ask for an example? Everything MB has ever put out has qualified their engine's compatibility with anything above B5.
The nearest MBS dealer than can take a Sprinter chassis is a couple of hours from me. For my oil changes I use a local repair shop that specializes in German engines. They have service bays that can easily fit my Solera, and they use the recommended fluids. Obviously for warranty or specialized work, we would go to an MBS/Sprinter dealer.