Everyone's safety would have been better served if he'd kept his butt in his vehicle, apart from probable cause.
You seem to not want to acknowledge that. Here's a little known fact YOU don't seem to know...in America, the state isn't supposed to bother you without a predetermined reason. What the hell do you think "rule of law" means?
An officer does not need probable cause or even reasonable suspicion to approach someone. To briefly detain and question and frisk, they need reasonable suspicion.
Probable cause is only needed for an arrest, extended detention or a search.