Well, yeah, sure. Tesla could respond with that argument … if they show up.
However, there’s a big problem with the argument. Failing to fulfill your obligations under a contract doesn’t let you just unwind the contract. Otherwise, lots of parties would just not fulfill their obligations. Tesla would like respond that your sole remedy is to cancel the order, but there plenty of reliance at play which makes that a poor argument. Waiting almost a full year and choosing not to purchase another vehicle means you relied on Tesla‘s promise to sell you a Model X. And Tesla’s constant missed estimated delivery dates just reinforces that they kept making promises that they weren’t keeping.
The fact that someone took delivery probably doesn’t make much difference. It doesn’t automatically mean they accepted all of the implicit conditions that were created by the other party. The other party can still be in breach. If you are buying a house and the other party breaches the contract by not signing over title in time doesn’t mean that they aren’t still liable for any damages when they ultimately do sign it over.
That’s how I would argue it. But I also intentionally chose not to accept a 6 seat upgrade on my LR under the promise that I would receive the X before the end of 2021. Doesn’t mean those who did weren’t mislead - unintentionally or not - to agree to a change.