In a certain sense, he's right. Starcraft's units may be well balanced, but it is easier to do some strategies than others. For instance, A "cannon rush" was the easiest protoss strategy against terran players (the easiest strategy in the game, TBH) because the zergs had the creep to block building next to mineral line and the protoss could just use the same strategy. Meanwhile, the MMM terran strategy (Medivac/Marine/Maurader) would be easier against protoss than zergs becausethe zergs have the combo Hydralisks+Roaches that decimate those squishy terran units. And, as every race has their weaknesses, the Protoss would fare better against the zergs with a 8-portals rush (while the massive number of squishy ranged units of the terran could handle that) and the terrans with a good number of siege tanks. This all is what makes one think a certain civ is better against another one.