Wahtever errors Beard committed, the quote rings true for today.
That he said it, when he knew that he was misrepresenting the motives and aims of the very Founders he was quoting, makes his an even more interesting and very twisted comment.
Yes, he may have been considered, in fact, a "very dangerous citizen" if he selected certain "phrases" from the Founders in order to attribute motives to them which did not accurately reflect their intentions in establishing this great Republic.
That does not, in any way, make it a less accurate statement today about how the current Administration demonizes Tea Partiers who simply use the Founders' words to advocate a return to the Founding principles. I just found it strange that Beard, of all people, would be quoted in this setting.