Two things -
Shaq was clearly within the restricted zone, so the call was an easy one to make and no arguement could be made otherwise.
Second, back in his Laker daze, or Orlando daze, I do not belief he had to worry about any restricted zone, since that came into play more recently, and, if I recall, bacame the new rule because Shaq would plant himself under the basket and swat the littlons back into the cheap seats every time they came into his play zone.