Actually, the clock keeper played no part here. The NBA has rules regarding what can and cannot be done in parts of a second. With 0.3 left, a player cannot catch and shoot. Any shot must be a tap. With 0.4 left, a player can catch and shoot, but it must be done all in one motion. No turning. With 0.5 left, something else is allowed - I forget what. The point is - Fisher did exactly what the rules allowed, and therefore the shot is good. The timekeeper actually plays no part in plays with less than a second left.