Your example explains how the rules work currently, but what about this example:
PUM! Me whack you hard with club (blunt).
Me whack Ogryn very good (critical).
Your Armor is weaker than it used to be (or whack was even stronger) (you make one Save, still have 2 Wounds left)
You whacked the Ogryn too hard to let him walk like drunken Grot, so ogryn is not KD.
I'm not talking about fairness here but whacking ogres. Iwas just wondering why a WEAKER hit (both wounds saved) should have a stronger impact (walks like drunken goblin) than a stronger hit which actually deals damage.
The rule as it is written works perfect for models with only one wound in their profile. If they fail but one armor save they are at least KD anyways. More likely stunned due to the +2 to injury rolls.
But a Model with 2-3 wounds in the profile profits from NOT saving a wound and this just seems weird.
Maybe you should rephrase the additional effekt from:
If the opponent successfully Saves both Wounds to
If the opponent still stands after the attack, then an ogryn could not cheat by taking down his helmet before being hit on the head

It won't have a great impact on the game (if any) but it just feels fairer (ok, it IS about fairness

).
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play the game - not the rules