There are some nuances in the wording. Traditional "pushing", is underexposure/overdevelopment. Thomas is referring to more of a compensating-type development, where using a more diluted developer, with longer development times and reduced agitation, helps maximize (though not necessarily push) shadow detail without blowing highlights. Traditional pushing in full strength developers tends to give you an upswept curve, with contrast increasing more in areas of high exposure. Compensating procedures are an attempt to do the opposite - ie preferentially develop the shadows without increasing the highlight contrast too much.

Actually this is why if you can tolerate more grain, some of the best developers for maximizing film speed are high acutance formulas, because they are naturally compensating when used normally. Note this is maximizing real film speed, not pushing. With traditional films you can sometimes get up to a full stop more shadow speed with these developers while not blowing the highlights.