Here's what I don't understand:
The OP says he's in a high-dollar business yet immediately jumped to legal threats, and this surprises me. Very, very long ago - in my very early 20's - I was taught that the best course of action to take the moment a customer threatens legal action is to cut off any communication immediately and suggest the customer follow through by having his counsel contact your counsel where all of the legal maneuvering can take place. In this case, the customer made a legal demand of $30k and threatened to sue. I don't blame Tesla and its counsel here at all for its response. It is never appropriate to threaten legal action unless you're willing to follow through on it, and when you do threaten the action you'd better make sure that the law is on your side. At every turn, Tesla has consistently demonstrated its willingness to make things right, but the threats kept coming with unreasonable demands.
Second, there are times when, frankly, it's better not to do business with someone - especially if they take an adversarial and/or litigious position on every business dealing. I recall Herb Kelleher's response to a woman who consistently complained at Southwest Airlines after every flight and kept threatening never to fly them again. After many different letters from Southwest's customer relations team to the woman explaining policy, Herb Kelleher (CEO) finally responded to one of the letters... "Dear Ms. Crabapple, we will miss you. Love, Herb." And, frankly, that's the right attitude to have.
And finally, after reading the e-mail, I sincerely doubt that anyone in the stores said that Model S was never going to be released with "AWD or anything else". The sales staff aren't aware of the car's unannounced future specs, and as such it just doesn't make sense for them to say definitively there aren't any plans. In fact, on more than one occasion I've heard Tesla sales staff say that their purpose is to demonstrate what's available today, not speculate on the futures - which come from engineering.
Tesla has the concept of "due bills". My car was delivered without my rear-facing seats, and Tesla told me that they would be installed when ready (which turned out to be about 2 months later). It was listed as an item that would be addressed in the future and was agreed to -- as well as the pano sunshade and a few other things. Tesla *did* commit to the new seats but that wasn't good enough, and rejecting the vehicle delivery instead of working with Tesla is indeed a justification for canceling a future reservation for another vehicle, as long as the deposit was refunded.
