I don't understand any of this. What's the contradiction?
It's based on a weird premise too (obviously) but the vagina relaxes for a reason, to take the penis for which it may need to relax further before constricting on it. It just doesn't flop open and stay open. (I should note that Kevin is familar with the opposite problem.) It's a system of muscles, dummy. These things have evolutionary, not rationalized, reasons for doing what they do.
It's such reasoning backwards too. The reason a vagina (or penis) operates the way it does is for reproduction. Sex is pleasurable to promote reproduction. This doesn't mean pleasure is the goal of your sex parts, it's something humans are able to reason about conceptually. "Oh, shit, I can do this just because it feels good!" Look at animals, how many of them have spikes or other harmful shit in their sex parts? And their mating looks, sounds like or is closer to rape. Kevin looks at these and goes "oooh, slutty kink play" probably. Yeah, okay, then why don't they do it as often as humans do?
Also "tight pussy" isn't describing the mechanics of things it's describing a personal culturally superior version of things, like your other muscles being swole or whatever. It's based in the human reasoning of the pleasure aspect, not the biological function. There's no necessarily biological need for a "tight pussy" to reproduce. It's a sociocultural claim about yourself.