I didn't see the justification, that being said, the video was not complete so I don't have an informed opinion. Now I think he might have been trying to get both of them out of the road by his actions, personally, being a non LE type, I would have let her stand by the road and let the video and audio record my trying to get her to move and let her roll the dice with the traffic.
However, the actions of the woman were deplorable,and stupid. In recognition of what Timothy posted, I am not going to act the fool around someone who has a loaded gun and other "instruments of compliance" hanging off his belt. You really don't know what kind of day this guy had.
If this woman could see the cops life over the past 24 hours, what could it have been? Maybe he is a functioning alcoholic who is still a little drunk. Maybe being a little drunk makes him pissed off, or because he found the dog had chewed his holster, the cat crapped in his shoes, he was passed over for promotion, his ex-wife just won a huge alimony decision because his wife had a snake of a lawyer who was hired by his evil ex-mother-in-law. Who by the way looks like YOU, YOU 72 YEAR OLD HAG!!! AHHHHHHH! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! BLAM! Click... (reloading sounds) BLAM! BLAM! BLAM!... well, you get the idea. Cops are human too, if you are smart, you never forget that just because they are trained doesn't mean they don't have the capability to divert from that training in a split second.
Let's be safe out there!