I find it difficult to follow the arguments but for the technically minded...knock yourselves out.
here is a 'tell' - Mann now says it's a 'myth' of the hockey stick that it implies temperatures are higher in 20th century than at any time in 1000 years. hmmm, check that with the popular descriptions and scaremongering on global warming.
So M+M tell us Mann is wrong, get rejected by the 'in-crowd' at Nature, and post it for others to see ... and Mann feels the need to post retorts on the web as a way to wage his own PR campaign. I smell defensiveness. As Gomer Pyle would say - "surprise surprise".