re: the main point.
The point is not how credible Beckett actually is, it's that most of those accusing the veterans of lying accepted Beckett at face value.
As for your question about the veterans:
If you check out their website, it explains who is saying what. Try the FAQ.
The letter signed by a large number of veterans can be read here.
As was mentioned elsewhere, if 200 Alabama National Guardsmen had signed a letter similar to this, it would have been on the New York Times front page for two weeks.
