Mr. Beck is a political commentator not a historian. His facts tend to be cherry picked to support his political agenda. He rarely outright lies but he does use quotes and facts with improper contextualization and is prone to using facts which are not properly supported. His association with discredited academics such as David Barton do little to improve his credibility with serious historians. (David Barton's book The Jefferson Lies was pulled by its publisher because of unsupported facts the book included a foreword by Glenn Beck)

A short answer is that Mr. Beck would likely find himself banned from AskHistorians for repeated soapboxing and unsourced answers.

I have a similar question about Bill O'Reilly's "Killing..." series.