User blog comment:Omega64/Is Shizu actually Lucia's Reincarnation?/@comment-36209226-20190124201801

I think Rimuru not being of this world originally, restored the balance and objectivity that Veldanava lost. You'll notice that Rimuru loves all equally and plays no favoritism. It is for that reason that the two Ultimate Skills were allowed to manifest in him. Also consider this, The World Voice (which behaved and sounded just like Great Sage) spoke to him prior to reincarnating in the Great Jura Forest. I think he was chosen as the conduit for the power of Valdanava.