from the looks of it, he pruned OFF the bottoms. (almost) I'm assuming this encourages enough outward growth, and side-shoots and any previous leaf damage (from lower light under the tops, or algae spotting) would be completely hidden by the new growth. not to mention when he topped the plants the first few times, I'd assume he had the option of using those stems to hide some of the problem areas if indeed there were any.
or maybe he's a much better aquarist than I am and never sees algae (although his first posts reveal he is indeed human)
Nice "writeup" by the way, although I know that's not what the pics were meant to be. Still nice to see the trim technique even in a vague sense, and then see the results on a timeline like that.