sheldon certainly knew A LOT about bikes, but he was not infallible. i highly doubt his statitic that ALL "skilled cyclists" use only their front brake 95% of the time. there's a crapload of subjectivity that goes into a statement that bold.

i easily consider myself a skilled cyclist and when i apply the brakes on any of my bikes, i usually apply braking power to both the front and rear wheels. when i need to panic stop, i move myself off the back end of my saddle to put more weight over the rear wheel to increase stopping power of the rear brake, while also taking my front brake to the limit of safety, ie. brake hard up front, but not enough to be thrown over the bars.

on my featherweight road bike, i also like to slam my front brake super hard right at the very end of the braking process to lock up the front wheel and lift the back wheel off the ground a couple of inches for dramatic flair. the maneuver is a little dicey if you're riding clipless and you don't have good clipping out reflexes