Definitely not. For starters seating position is different. A sport bike rider sits more aggresively, leaned front. Rider has more weight on the wrists (due to position) and it allows less maneuveribility at lower speeds. On a crusier, the rider sits more relaxed and its easier to turn the bike at lower speeds. A good compromise would be a standard bike (which unfortunately, there's not a lot on this side of the pond).
Also acceleration rate is different. A 'sport'bike is made to go fast, they usually have a more sensitive throttle with quicker response and hence are not recommended for beginners since they leave less margin for error.
Seats on cruisers are lower which mean a new rider doesn't have to fumble to get his/her feet on the ground. They also usually have a lower centre of gravity which makes it easier to carry the weight of the bike at slower speeds.
That being said, I think a 600cc cruiser would definitely make a better learner bike than a 600cc sport bike (which I wouldn't recommend anyways). I haven't actually rode many cruisers so I can't say much, but I'm sure the cruiser riders on the forum would be glad to make suggestions. Just my 2¢
BTW I'm glad ppl are actually taking the time to read the article ...