It tends to depend on your goals. People doing cardio for the purpose of leaning out are generally doing it to deplete muscle glycogen and initiate lipolysis (so called "fat burning"). Avoiding CHO for an hour or so following cardio is thought to extend the period of time that the body is primarily tapping into those fat stores.
In theory it sounds good and it may work well for some people and not others. Experimentation is the only sure way of knowing for yourself.
Also, if you're primarily doing cardio work for the health benefits and not so much to "get ripped" it probably isn't anything to worry about.
I'm a firm believer that total daily calories vs. total daily energy expenditure is the bottom line when it comes to weight loss. Sure, there are little tricks and tweaks that you can employ - but if you're eating clean foods (and, perhaps, most importantly, not over-eating) and maintaining a strict workout regimen you should see results.