I've been riding clipless since LOOK came out with pedals around '86. I completely "get" why some folks don't dig them, but Grant's arguments are BS. If he doesn't want to use them fine, but his whole psuedoscientific muscle training theory is just so much wishful thinking. Further he shows his ignorance by assuming why riders choose to use clipless pedal. (ie: cyclists use clipless to be faster, clipless don't make you faster, so don't use clipless)
For me it's just being better connected to the bike and this makes me faster because my feet aren't slipping off the pedals when I'm hammering in traffic.