I think that is only part of the reason why employees are getting the first Model 3, and a minor part at that. In my opinion, the primary reason that employees got first chance at reservations and delivery (if they are in the US, I assume, not sure about overseas employees) is that the Model 3 is the first Tesla that the average Tesla employee can afford, and this is Elon's way of saying "thank you" to the thousands of Tesla employees who have worked so hard to create and build and deliver previous Tesla models. So far, most employees have not been able to afford to purchase the products they are working on! Most of them will be able to afford a Model 3. So they are being given first chance at buying one. Which I think is wonderful. Tesla did not have to do that. Tesla could have simply prioritized deliveries based on distance from the factory no matter whether the delivery was to an employee or not, but chose not to do that.
I agree that US west coast delivered Model 3's can potentially be fixed more promptly if unanticipated problems occur, but do not agree that all current owners are more "forgiving" or "loyal to the brand". Many are, but many are not. Again, I think Tesla is prioritizing Model 3 orders from current owners as a way of saying "thank you" to their customers.