I don't think anything should be read too deeply into what Lucas intended to do or say. I know this will sound like ye ol PT bashing, but Lucas is a weak writer.
He wanted it to be clear that Anakin is ultimately corrupted by his inability to have any chill. He framed that by way of Anakin struggling with attachment. The idea that he is "too old" is the easiest way to just tell the audience that he is too emotionally attached to his mother.
It's just like he needed a way to make it clear Anakin was super special, so he makes up a midichloriam test.
When he had no one to answer to, studio or producer, and the added benefit of having made the Jedi up, he could get away with just calling his first, most on the nose ideas done.
I agree Lucas is a big picture type of writer who has good ideas, and when it gets to actual details, he is weak. He probably should have left the finer details to better writers, which does explain what happened with the PT, because he didn't. Many issues people have with the PT is valid. I am not going to defend that at all.
But, I think when it comes to my original response to Filthy Jawa, and without invalidating what you just said (because it does make sense and I agree with much of it) I still think that at least some of what I pointed out about knights, samurai, and shaolin monks could be what influenced how he depicted the Jedi Order. But again, just a theory on my part. Only Lucas could really answer that, and I haven't seen anything where Lucas stated anything to back my theory up. My theory is mostly based on making comparisons of how the jedi were depicted by Lucas, to real life examples of real monks or warriors.