Dave,

Without scrolling back up to check, I think the arguement goes as follows:

On finding a 'googlewhack' you've found the only document on the web that contains those two words.

By the nature of your announcing it to the web community, you've created a second webpage that contains those words, hence it will no longer be a 'googlewhack'

In reality it isn't that simple, but I hope that answers your query

Ed