The story also discusses both of these points. The other guy did get into his Tesla:
> That means, if you’re following along, the other guy was able to gain access to Randev’s Tesla as well.
But it wouldn't make sense both Tesla's were just unlocked and started at the same time since he was later able to unlock and start the Tesla a 2nd time:
> The two Tesla owners made a plan to switch the cars back — after Randev picked his kids from school. That’s right: Randev was able to get into the Model 3 that wasn’t his, and drive away, for a second time.
(as a side note both of these are worded much better in the original article). It also says he has video evidence of the issue he was trying to deliver to Tesla but neither article includes that video so I'm not sure I buy a simple solution without evidence the entire thing was just fabricated.