No he's right. The solution for an optimal surface area to volume ratio is a sphere. The farther you deviate from a sphere the less optimal you become. The actual math for this is finding deltaSurfaceArea in respects to cylinder radius for a given volume and then finding the maxima, which is a Uni physics 1 problem I really don't feel like doing. Long story short, optimal is when height = diameter, or as close to a sphere as a cylinder can be.