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I think you're making interpretations of things I didn't say. I did say the following:

However, given that there are independent analyses of climate proxy data that show the same general patterns as the Mann et al. papers,

and

The argument is that his data analyses reduced the apparent scope and intensity of the Medieval Warm Period warmth and the Little Ice Age cold.

So was I skeptical about Mann's claims? I guess the central claim then was that this period was the warmest in 1000 (2000?) years, globally. Whether or not I was skeptical at the time (I don't remember how skeptical I was or whether I really concerned myself with that particular claim), I was unsurprised when it turned out that there wasn't very good data allowing any quantitative comparisons going back more than 400 years -- hence you can't say that the MWP was warmer than now or vice versa, you can just say now and then were both clearly warm periods.

So now the question might be posed: what about the most recent paper (i.e., Mann et al. 2008)? If I read Climate Audit correctly -- and I haven't bothered with the new paper -- then there's only a "skillful" reconstruction back to 1500, so any results before that are not "skillful". If that's true, then I would think any direct quantitative comparisons are still kinda stupid.

And I will note, as I know I've done numerous times before, that it's not the actual value of the temperature that's as important as the rate of change. Looking at the paleoclimate record solely as an indicator of when abrupt climate changes happened and not concentrating on absolute temperatures, it is clear that times of maximum ecosystem disruption occurred at the times of most rapid climate change. (Unsurprising.) Knowing what I purport to know (and what I think I know) about the current climate indicates that we are on the verge of a very rapid climate change. And I know what that means for ecosystems.

So what about Mann? In summary, he got hired to do a job. He's doing that job by continuing to publish in the field that the university which hired him expected him to publish in. Unfortunately, the controversy that has dogged his earlier efforts has made him a lightning rod, and any further criticism that sticks (and some of it might) will serve as a further example to those who are aleardy convinced of it that the whole scientific understanding of global warming is unsound.

And since I know that's utterly idiotic, there's no point in my pursuing the arcania of centered or non-centered PCA. This is a sideshow. The main show is going on under the big tent.