No, but it is an applicable analogy. A great deal of research has been expended to extend combat swimmer’s capacity. So what information -can you provide to support your statement that the frog kick is more efficient?
So, you're suggesting that research done on some of the most physically fit people on the planet, in likely ridiculously demanding situations, is apples-to-apples applicable to the average recreational diver who wants to look at pretty fishies and then go have a pina colada?
I can only imagine what it would be like to be an out of shape, handful-of-dives-a-year, recreational diver doing a p***-poor bicycle-style flutter kick with crappy fins... desperately trying to keep up with navy seals and Michael Phelps.
Admittedly, all I've got is my own N=1 study. But as a lifelong competitive swimmer who logs 3,000-4,000yds four days a week at a 1:25 pace and roughly 100 dives a year I can tell you that while my flutter kick is highly efficient in the pool, pushing my FastSkin3 jammer-wearing, silicone-capped, Swedish goggled, shaved body through the water... it's not worth much pushing my steel doubles-toting, deco/sling-bottle carrying, drysuit-clad, Jet-fin wearing body through the ocean. On the other hand, my picture-perfect, high-torque, albeit leisurely paced, frog-kick (which does just fine on reefs and in wrecks and caves) would be pretty sh***y if I was asked to anchor the freestyle leg of a 4x100M medley relay.
BTW - the arms do the vast majority of work in freestyle swimming. The reason the flutter kick is most efficient there is that it keeps your legs/feet largely within the slipstream of your upper body. As you've pointed out, drag is proportional to speed. The flutter kick is efficient because it reduces drag at freestyle speeds. Breast-stroke, on the otherhand, is an "arms AND legs" stroke where much of the speed comes from the high-torque whip of the leg kick.
One kick is not "better" than the other, they are each simply more appropriate given the circumstances.
Horses for courses.