Not a lawyer, but in addition to the reliance damages, there is something called Expectation Damages which is based on the principle that once a contract is signed, if a party breaches, it needs to compensate the other party such that they are in the same place they were had the contract been completed. However, this would likely be cash. More directly to your question, Specific Performance exists as a remedy that could allow a court to force Tesla to complete the contract. It seems as if the attorney is suggesting this remedy given his reference to the “very unique product” and that they need to “perform as they promised and agreed.” You raise a very valid point about why some may not want Tesla to complete the work, and that kind of concern is why specific performance is an unlikely remedy. The only other thing I could see would be the possibility of punitive damages if they “violated consumer protection acts” as the lawsuit claims.
I am not suggesting any of these arguments are necessarily likely to succeed, just that they exist, and I would assume the attorney will at this stage be putting forward all possible arguments with the hopes of improving their chances for a favorable settlement or judgement. And, as to the point raised above, some of these arguments may also be intended to help invalidate the arbitration clause, which will be necessary to allow most of these potential plaintiffs to proceed. Otherwise, the contract calls for binding, individual arbitration.