Goodness, but we are holding Palmer to a high standard here! I took his comments very simply to be a very honest man looking back at his career and expressing a regret, and maybe even setting a goal, and I don't know of too many 74 yr. olds who couldn't do the same. I would also imagine that most, if not all, working architects, hope that the best is yet ahead, and/or that they wish they had done some things differently.
If, in fact, his courses are not rated highly in large part because of housing (and LOTS of it, I grant you!), doesn't that say a lot more about the ratings than what his design firm evolved to?