[It's only a speculation. I told you, I am not entirely omniscient.]
Torn by the sudden uncertain information, Maximilian couldn't fully seem to reject that speculation.
It could be false, or it could be true. Either way, he already decided to find a way to see if the Goddess were someone to be trusted or worked with.
However, there was no information about her. Except for being just a sudden Goddess of this world, Maximilian found that one of these two Gods can be lying.
Shi: [Since you were able to reincarnate from inside the world barrier into another time, I'll send you back to your present time. You are ruining my world's flow of natural balance.]
But hearing Shi's elaborate but arrogant answer gives Maximilian the impression that Shi was indeed the creator of this world, given that he had only intervened spiritually by taking him here.