I haven't read about that, but I believe I know why he says that.
Omega 6 is linoleic acid. On the pH scale, omega 6 would be less alkaline and much more acidic. Acidic substances in your diet tend to cause inflammation.. Foods like beef, etc. with high fat concentrations can cause inflammations and on a nitty-gritty level, lots of BBers tend to eat good quantities of foods containing zinc and calcium; two elements that are far more alkaline. An example would be spinach. A general rule of thumb when you really get hardcore into healthy eating, is to balance all your foods on the pH scale, so as an example, for every acidic portion of food you eat(beef), balance it with an alkaline food(spinach).
Meal to meal it doesn't matter very much, but over months and years, you'll likely notice strength/size benefits if you balance the acidity of your body.
edit: that may have been a little confusing, but I'm sure some of the more experienced guys here will know what I'm talking about.