The posted web site date was probably from a correctly set system, because it was picked up by google’s caching the next day. That verified that it was posted BEFORE the shootings. Capiche?
Where are you seeing that the “posted web site date” was picked up by google’s caching the next day? What evidence do you have that the posted web site date for the fundraising page (December 11) came from a different source than the posted web site dates for the other pages (July, Sept, Oct)?
Nope. The date listed is not the date Google spidered the page.
It's the date Google's indexing algorithm decided to assign to the page. Figuring out page dates is not one of Google's stronger points. But, to be fair, it's a hard problem, given web authors can put whatever they want on a page. Actually, it might be nice if Google would actually let you select on the cache date. But they don't, as far as I know.
You encounter this problem whenever somebody relatively obscure suddenly finds himself very much in the news for whatever reason. The natural impulse is to do a Google search on the person with a date restriction ending just before the newsworthy incident, in hopes of avoiding all the redundant news accounts, blog posts, and tweets and actually turning up something worth knowing about before it gets scrubbed. However, because of its imperfections, Google's date filtering rarely cuts down the clutter enough to be helpful. In such cases, I find myself turning to Yandex, where their bug — less frequent spidering — becomes a feature. They don't have the clutter simply because they haven't yet got around to sucking it into their engine.