I'm a bit confounded that you were able to open its port but not able to plug it in. That suggests - absolutely not definitively, though - that the vehicle itself has a problem and therefore it might be the case that the driver isn't being a complete....aah...unpleasant fellow.
That said, even were that the case I would say it's bad form to have left the vehicle blocking others from using the site.
Did you take a look at its VIN#? On this side of the puddle, I've noticed that most-recently produced Teslas have owners who are less fastidious in Doing The Right Thing than are older ones. A generalized observation, of course.