I agree with you. People went to the trouble to look up the quote, it wouldn't be that hard to paste in the web page they found it on.

OTOH one can always enter the quote and see what turns up, like this link: counterpunch.org/2005/0…

Then you go down a rabbit hole of other links that will deny the quote.

In the end, there's no real way of being "sure". It is all a question of narrative and who writes the history. With the Oligarchy working so hard to maintain US hegemony though, it becomes easy to believe the re-written history.