'I must admit that I have underestimated them. None of us that break limits are ordinary. I shouldn't have underestimated them.'
He had underestimated Legion. He wasn't overly impressed with Legion when it broke the first law. The reward he got was mediocre. It wasn't powerful. As a realm lord, clones didn't matter to him. He would have been bothered if Legion could create infinite clones. A flimsy number of 8 clones didn't impress him even if they reincarnated. He has power and nothing beats power.
His disdain increased when he discovered that Legion was researching the Authority of gods. He already figured it out and broke a law of the universe for tracing Authority to its roots. Now he can create and bestow Authority on himself or whoever he wants. It is a really important thing because the scope of Authority is far larger than what Legion knows. Even world gods are interested in his ability.