Someone please explain how being able to tread open water for ten minutes does not equate to "swimming"? And if this is not swimming, what does it take to meet your definition of swimming? When my wife was certified by PADI two years ago, she had to tread deep water for ten minutes without stopping, not float on her back, but tread water keeping in one position with her head above water. This is no trivial task, and could be challenging for any trained swimmer who is in poor physical shape.
While I agree that anybody taking up diving should really be 100% comfortable in the water before learning to dive, how much more should a person have to demonstrate besides being able to cover distance, and keep themselves afloat.