You miss 5 fouls committed against Shaq, that's 4 points lost at most. You miss 5 against Yao, that's 8 points lost. Big difference. Game-changing difference.
That was very blurry and small. Face it, the referees hate big men. The bigger the Center, the less calls he gets. Yao and Shaq have big targets on them, because they are the biggest and strongest. The referees will let a 6'10" PF to tackle, wrestle, and claw him. The only respect he gets is against 1st and 2nd year Centers/Power forwards.