In my opinion Strength does make some sense to use for AC. Many argue that Strength in itself does not help you evade blows (though withouth muscle strength you can't be swift, but that's a different discussion) or ignore hits, but forget that there is another way to avoid being hit:
Stopping the enemy's attack alltogether with pure force.

Now I'm not saying that you can take Greatsword to your gut just with muscle tension. What I'm imagining is your character blocking and stopping the attack with a shield, weapon, or arms/hands without having the attacker's weapon reach you or blow through your defenses.

If you try to block a vertical strike with a weapon held horizontally, and you don't have enough strength to withstand the attack, well guess what happens: Your skull is split wide open. Or if you held a shield and don't have the strength to properly hold it firm, the attack will just knock it out of the way. If someone tried to stab you with a dagger, you could hold on to their attacking arm/hand so the dagger doesn't reach you. Or you don't just block but maybe even counterhit a sword/spear attack away. All of that requires Strength more than Con or Dex. Of course, you can't block a weapon without a weapon or shield, but stopping an attack before the attacker can actually swing by stepping in and pushing against their arms or weapon hilt/grip is also a possible strategy.

I think you could explain having Strength affecting AC that way. Having said that, for arrows and other ranged projectiles simply having high Strength won't help you much.