Well, I had typed out my reply in your eariler post but got disconnected from internet.
So here I go again.
Nitrogen cycle in a tank requires presence of ammonia, this gives rise to bacteria that convert ammonia to nitrites and subsequently to nitrates.
Now plants are said to prefer Nitrogen in form of Ammonia often nitrates, and will absorb ammonia as long as it is available in water.
Hence they directly compete with nitrifying bacteria for ammonia and hence it is often said that Nitrogen cycle will never even start in a well planted tank.
Hence I fully agree with your observation.
You can safely introduce fish in this tank.
In a non planted/less planted tank the usual assumptions of nitrogen cycle will apply.