there is no way to keep a cat from doing that, the one i had yould do it all the time, even it it did fall it would be fine..., cats can easly servive a 20 storry fall, unlike people.
Its there nature, im surprised that it didnt make it around the post.
bad owner my ass, it you tried to move the cat it would either fall down and be pissed off with posably a broken leg or it would jump on you and scratch the hell out of yah, trust me.
Another cute think mine would do is jump on my sholder and just stretch across my sholders or just sit there like a parrot while i walk around.