First off, there's a big difference between "heavy load" and "attack". You can usually tell the difference by looking at the network traffic, which I'm sure he had done, and seeing if there are lots of matching TCP sequence numbers (the sequence number is constant in the "industry-standard" syn-flooders for Windows).

Second, it's a tad strange that, for every time Bush is not a sure-fire winner, his site is attacked. That could be some bias, but that's what the webmaster says.