True the description in that thread calls that part a baffle but from the pictures it looks more like a support member (most likely supporting the floor rather than the hull). Any baffling action that that part will perform will be for and aft. The main issue on a sailboat, however, is side to side motion thus making it virtually ineffective as a baffle.
Baffles slow down the flow of liquid to minimize surge. They do not stop the flow. Even if the ballast tank had baffles when the boat heels the water will still flow to the leeward side of a partially filled tank thus loosing most, if not all, righting moment of the ballast.
Think of a 2 liter soda bottle. When the bottle is half full the fluid will slosh around as the bottle is moved in any direction. When it's full, however, the fluid inside doesn't move relative to the bottle (besides swirling when you spin the bottle which would have little effect on the boat). Thus the whole system of the bottle and fluid work together acting as one solid unit. This is why the ballast tanks must be full to function properly.
As Sumner said, "Since the tank should always be full I don't see a need for baffles from that respect."
