A slight tangent, but I'm curious, can Google claim the donation is from Google for tax purposes even though it's under the instruction of Nils instead of him receiving cash? If so, is that why they offer to double it?
That's pretty much the whole story. It was a quick email thread between a few people in Chrome Security and Google Security.
Not worth it for him.
Google could deduct it either way - either as a donation or as a business expense.
The rules for paying tax are different for corporations (which incidentally is one of the reasons some self employed programmers incorporate).
xkcd's take: http://xkcd.com/871/