The baking bread story is more on the order of a metaphor. It's a very good way of explaining to people the difference between a rye recipe bourbon and a wheat recipe bourbon. The problem with it as a form of discovery is that Samuels was familiar with wheat recipe bourbons. Though much less common than rye, they had been around for years. He knew some people, including his friend Pappy Van Winkle, used wheat recipes. Samuels didn't "discover" wheat recipe bourbon while baking bread.
I had lunch with Bill Samuels last Friday to talk about some of these very issues. He said the help his father received from Pappy was just the beginning. He also got help from Dan Street (Brown-Forman), Ed Shapira (Heaven Hill), Jere Beam (Jim Beam), King McClure (Stitzel-Weller) and one of the Motlows (Jack Daniel's). All of them at one time or another provided yeast samples. Pappy provided samples of new made whiskey so they could see how it was supposed to taste right from the still. One useful piece of information Pappy provided was that wheat mashes could not be cooked under pressure, as rye mashes often were. He says his dad always intended to make a wheat recipe bourbon because of the flavor.