Hawass has a number of nice articles on his site, he is actually quite a good writer.

But I question this notion that the Khufu grafitti is some kind of checkmate [or as scientists like to say "QED"] for the proposition that the pyramid was built by Khufu and Co.

Why is it stated as such? Aren't there other arguments or theories about how that grafitti could have been built after the fact?

For example the interior parts of the pyramid could have been built in part after the fact.

This would make since from the standpoint that the original builders had a completely different purpose than the egyptian purpose.