Disagree. If he was sure he would have said: "Of course we're going to show the actual car at the unveiling event".
I think it is most likely that Tesla will show
something physical of the Model 3 at the March event.
How much they show is the question.
This is commonplace in the automotive industry. Using Honda for example, because I am a Honda guy, when American Honda "revealed" the 10th Generation Civic design in early 2015, they only showed the exterior 2-door Civic. It wasn't until months later that Honda showed the interior and sedan design, and provided details on the new turbocharged powertrain. Even with the 10th Generation Civic now on sale, Honda still hasn't fully revealed the car: the 5-door hatchback, the Si trim, and the Type-R variants of the Civic are still under wraps until later this year.
I would expect that at a minimum, Tesla would show the exterior design, just like they did with Model S and Model X. I would also expect some detail on the expected range and/or battery capacity, and motor options (RWD, dual-motor, etc).
I would not be surprised if the interior design was hidden and/or incomplete or shown in concept pictures only. I would also expect specific features may not be disclosed, such as availability of the HVAC biofilter system.
I don't know if they need an alpha prototype to roll something onto the stage. I can't remember with the Model X if the alphas came a while after the reveal....
The Model S "reveal" was basically a body and interior concept built around a torn-down Mercedes S-class. The Model X prototype was shown around for years, and we only saw alphas when street testing began (the infamous video of a prototype doing burnouts on a parking lot near a shipping container vessel).