I'm saying that if a story that was as widely reported as that story was had been incorrect, there would have been a bunch of people stepping forward to say it was incorrect. As happened to Dan Rather & CBS. But nobody denied it. And apparently, GHWB was even given the chance to deny the comment and didn't.
I don't remember anyone at the time questioning the veracity of the quote. And even now on the internet, I can't find anyone (other than here) who doesn't think it happened and verified. Wouldn't pro-Bush groups have come out and defended him? If it's an urban legend, it's clearly one of the most pervasive ones out there...