Again, that's not what I see in the article (whether it accurately reflects reality is another issue). Here's the quote from the article:
"It began with a driver’s careless migration into the curb lane and my realization that I was about to be squeezed off the road yet again, or sideswiped if cell phone guy decided to turn right. A yell didn’t get his attention. The door punch did."

He explicitly states that he wasn't able to verbally get the motorist's attention but that physically hitting the car did achieve that.

And the article gives no clear indication of the cyclist's lane position and whether he was riding near the curb or in a 'taking the lane' position. I've been squeezed onto the side of the road by inattentive traffic moving into my lane both while cycling and while driving even when I was taking the lane in both cases. Yes, it helps to have a buffer zone to the right. Since the cyclist in the article did not end up colliding with the car he may well have had a sufficient buffer space.