I'm sorry to say, but most professional bodybuilders are full of crap. They like to assume that because they practically live in the gym that they're pros on how everyone should work out/diet.
You have a window within a couple of hours after a heavy liftin' workout to feed your muscles before they start cannibalizing the rest of your body. If you eat enough protein during this time, your muscle will definitely grow to adapt to your workout style. You don't need to stuff your face the minute you walk out of the gym though. This may even be counterproductive because you want blood circulating to your muscles after a workout, not to your gut to digest your post-workout snack. Give the muscles a chance to rest a bit.