You need to learn about Magic mana. Because you are flat out wrong and still too stubborn to go look it up. Its over 5 tiles for the 1x and over 11 for 2x. Of course you can bring those down to 5 and 11 with mana bonuses. But you can do the same with Wilbur to get him down to 9. The simple fact of the matter is his Def- is slower which is exactly the point you contended.
The argument is not whether you would use Kornel if you didn’t have another Fire Def Down option or you are fighting weaker titans where his survivability isn’t an issue.