I think you are missing a tiny point, you are comparing being able not to drown to swimming efficiently. I didn't bike in ages, but I am fairly confident I can

I think you are missing a tiny point, you are comparing being able not to drown to swimming efficiently. I didn't bike in ages, but I am fairly confident I can ride a bicycle all right. To go back doing cross country biking is a different matter, I will probably need to make mental efforts to keep the right posture, to keep the weight over my back wheel etc. But this doesn't mean I won't be able to ride my bike without crashing.