The idea does not eliminate the hurricanes it modifys them to a much weaker state no more than a catagory one by regulating the SSTs. The transfer of heat to the mid laditudes still occurs. The ocean temperature is regulated between 70 and 75 degrees and therefore as the storm crosses the cooler water it just weakens but it is not eliminated. BTW during the winter the temperature of the gulf is below 70 degrees so this should not harm sea life.
Tornado's may not even form in the mid west because of the cooler temperatures in the Gulf thus cooling the warm air migrating to the North out of the Gulf Of Mexico. Since the air is cooler not as much lift is created in the atmosphere for tornados to form.