I think the kid got attacked because he wanted an answer to a very specific question, but I could be wrong. He got his answer anyway.
What I'm actually curious about is why nobody questioned the comments about speed and bicycles. I think push steering, or counter steering, happens WAY sooner (ie. at a lower speed) on bicycle.
Picture a child learning to ride. They ride around for while on tricycle, then they ride around with training wheels. As long as the training wheels are set level or almost level with the rear wheel, it's still at least a two-track and likely a three-track vehicle - so steering is the same -you turn in the direction you want to go.
Watch the kid when they switch to two wheels and get up some speed. You'll see some experimental "jabs" on the bars. Why? Becuase as soon as they start to move the bars, the bike goes the opposite of what they expected and they instinctively correct it. In 3 to 5 minutes, they figure out push steering.
Maybe wheel diameter has something to do with it. Remember when everyone had 10 speeds (am I showing my age here? They were shaped like road racing bikes) instead of mountain bikes? Doesn't really matter about the bike, but remember how cool it was when you could ride forever with no hands, just sitting up straight? If you wanted to turn, you did it with your hips - a quick shift in the direction you wanted to turn. What happens to the handlebars? They flick quickly in the opposite direction - the wheel points the wrong way, and forces that pivot, resulting in a lean in the direction you wanted to go.
That's why I think push-steering happens at lower speeds on a bicycle, nowhere near 30 kph. It's also an example I've used when I'm teaching push steering and someone's over thinking it. Anyone that rode a bike learned it without thinking - don't waste time thinking about it now!