Why was Holt's letter sent now?

In case you haven't noticed, the president of Grewal's riding association, Jim Holt, has circulated a long-detailed memo defending Grewal. The document is quoted here (with hattips to Public Eye Online and Bound by Gravity, where you can download the original Word file.)

My first post on this 'memo' (here) got one important fact wrong that I should correct here. Holt's four page memo was sent not to constituents, but to party members. That difference is not trivial. The memo is an impassioned plea for the membership to support Grewal. Why does Holt have to send this letter to them at all? Indeed, doesn't the very existence of this memo imply profound dissatisfaction within the rank-and-file?

Let us accept, for a moment, that this is the case. The question becomes, why now? The negative stories about Grewal in the press were much worse six weeks ago, when the tapes episode was at the height. Conservatives managed to remain moderately loyal to Grewal then. What changed?

My guess--and if you have a better idea please suggest it in the comments--is that many in the Conservative ranks were profoundly disappointed to see Grewal in the headlines again, just when it seemed the story might be fading from the public's memory. We've seen similar thing amongst the Blogging Tories. The story that Grewal gave new tapes to the RCMP (which has been clarified by Holt's letter) drove Brent Colbert to call for Grewal's head, as did the story about Grewal's electorial financing did for Andrew at Bound for Gravity. This latest story about Grewals' election also elicited a quick denunciation of Grewal by conservatives in BC, including MPs (see here). This is more or less admitted by Holt in his opening paragraph:

As you are very well aware, the past few weeks have not in any way been pleasant for our elected MP, for members of our constituency association, for the Conservative Party as a whole, and perhaps even for us as residents of Surrey and North Delta.

Now, Andrew has since withdrawn his criticism as overhasty; Colbert may well have, too. But that is not the point. Surely what is significant here is how many conservatives are turning against Grewal for what are not hanging offenses in the Canadian system.

Why now? The latest two stories -- on the surrender of additional tapes to the RCMP and about election financing--are merely the proverbial straws that broke the back of many a patient conservative camel.