Apart from anything else, Teslas all have security cameras in them - every direction from the car is covered.
So, sure, the footage wouldn’t survive the car being burnt out, but where’s there’s one Tesla parked there’s usually more (due to charging). There are several channels on YouTube that publish incidents of vandalism against parked Teslas as well as traffic incidents Traditionally, the vandalism would be done by rednecks and boomers, who you tend to assume are Trump voters.
Occam’s razor says Musk is lying. He continually spreads lies when there’s any doubt to be profited from - take the recent example where he insinuated that Ukraine state actors were behind a ddos attack on Xitter.