Claiming that aluminum is not brittle because it's used on airplanes is silly.
It would be, but this statement is attacking a strawman, since none of us claimed it. For that matter, I suggest rereading my post for any mention of Aluminum. You won't find any. I addressed Carbon Fiber. SuperBannana covered Aluminum, but your post agrees with him - summarized as various materials can be engineered to perform various roles, empasizing or minimizing various characteristics within limits.
As for Aluminum flexing too, I agree, I see it frequently. The difference is one of magnitude. Aluminum wings will fail at far lower stress levels and certainly less bend than CF wings. You also have the problem that Aluminum is known to fatigue far quicker even with less flex than steel, much less CF.
Steel is mostly good because it's cheap and has one of the more forgiving failure modes when overstressed.
The aluminum used on airplanes isn't different; it's a grade of aluminum suitable for planes, with some of aluminum's weaknesses more pronounced and some less.
Contradicting yourself here. Airplane aluminum IS different than what you'll find in something like a Soda Can. The alloy will be different, as well as treatment and forming techniques.