Does the fact that my SUV can carry more than my bicycle mean that the SUV is more flexible?

No, it just means that the SUV can carry more. The bicycle is easier to park; there are large parts of town where bikes can go but a car cannot; and the bike helps me live longer.

Obviously "flexibility" is not judged by selecting a single case that suits one's stance. If I need to get from A to B quickly, a helicopter may be more useful than either the SUV or the bike. Surely we all agree that it would be illogical to claim that a helicopter is the most flexible transport option for me, based on that single premise; or to insist that this single case forms an irresistable rebuttal of the assertion that some other option is most flexible.

I believe that the label for a single point, simplistic declaration is 'slogan'. Beloved by advertising types, but apt to crumble once logic gets a look in.