Asa Dotzler is community coordinator for Mozilla, I think he knows what he's talking about...
My interpretation is that 16 months ago, Firefox stopped caring about Acid3 because the remaining points were disagreements on how to interpret the standard. Not because they were too lazy to fix it, because they had a point.
The fact that it has been resolved only now is irrelevant. If you take a Firefox 16 months old and run Acid3 on it now, it would score 100% - I think that's what he meant.
AFAIK, Firefox has not introduced any change in order to score 100% on Acid3. If you read this article (http://browserfame.com/212/firefox-acid3-test-100), you will come to know that the developer of Acid3 test has introduced few changes in order to "update" the test. On the updated Acid3 scale, Firefox scores 100%. This simply indicates that Mozilla was correct!
I agree with you: "If you take a Firefox 16 months old and run Acid3 on it now, it would score 100% - I think that's what he meant.".
I am unable to understand your comment: "read before you respond stupidly.". Can you please explain my stupidity?
(FYI: I am also associated with Mozilla for long, as a volunteer.)
I upvoted you. Not because I think what you said is insightful, but because your post serves as a textbook example of a person who not only doesn't see how stupid and trollish his own post is, but also dismisses all forms of legit criticism as fanboyism.
Oh and don't forget he's ranting about how this site is going down hill while contributing nothing and pretty much making this piece of the thread unpleasant.