Hershey's chocolate syrup recommends that you "refrigerate after opening", but unlike many other sauces with this recommendation (e.g. ketchup, mayonnaise, BBQ sauce etc.) chocolate syrup bottles are not sealed when sold on the shelf (i.e. there is nothing under the cap to remove before first use.
So for these other liquids I understand the argument that the bottle is sealed at the factory and once the seal is opened bacteria can enter, but the chocolate is never sealed so this argument doesn't seem to hold.
Is there any good reason (Hershey trying to protect themselves from lawsuits doesn't count) why chocolate syrup needs to be refrigerated after opening?