Research (I'm not finding the studies, sorry) has indeed shown that protein intake is minimally correlated to muscle growth. He was on the mark by mentioning that only certain amounts of protein can be used in one setting, while the rest is wasted by the body. It's not one hard and fast number; individuals bodies vary greatly according to metabolic rates, capacity to grow, and ability to gain strength.
After going from zero resistance training to 90 minutes a week, as was his case, anybody is obviously going to get much stronger. In the strength community these are just referred to as beginner gains.
When you've been lifting for a few years, 90 minutes of strenuous resistance training a week is only going to help you maintain your current body, at best, even at maximal resistance levels and training until failure. This is why it's so common to see guys who go to the same gym for years and never look any different. Over time, your body acclimates and it takes more resistance AND more volume to continue growing. Genetics and the aforementioned variability between individuals does play a large difference, but for nearly anyone, doing three 30 minute workouts a week (at maximum intensity) for more than a couple years won't result in any noticeable difference.
If you're focusing time efficiency, go for it, else there are far more reputable sources for how to gain strength and muscle mass than one guy's anecdote of how he did half a year of strength training.