That was rash. You called the police within an hour of reading this article? You didn't think it's possible the writer is embellishing or exaggerating the danger he was in here? As of right now, everything they've done has been done in good faith to try to point out the need for extra security.
Also, if they get arrested, even convicted of a crime, then what? You have two extremely angry researchers who know how to hack your car, and what, you're hoping some jail time might help them see the error of their ways and use more caution in the future? You can't see any potential problems if one of them feels vindictive about being jailed over your phone call when they weren't trying to do anything wrong in the first place?