Correct me if I'm wrong, but it seems that the author's point can be summarised as:

Obscurity will (at least in the case of an SSH deamon) not make an attack any less likely to /succeed/, but it will make it less likely to /happen/.

Note that what he observed were automated, scan-everything-you-can, undirected attacks. I would presume that changing the SSH port will do very little against a targeted attack.

Who really knows, but it will certainly keep your log files cleaner and this alone makes it worthwhile doing.