Joining the machine pathway isn't something he is willing to do because he already has his mind set on another pathway, and he doesn't want to join the messy pool that is the machine pathway.
He knows that there is conflict in the machine pathway. The pathway is divided between the two gods.
He also knows that if he becomes a machinist, he too will be drawn into this division. It is a conflict that can cost him his life, so he decided not to take it.
He didn't say that to the god of steam, though. He only said, "Thank you for your appreciation, the great god of steam. Please give me some time to think about it."
He wasn't actually talking directly to the god of steam. His existence isn't strong enough for that.
He would die in the presence of a god. So the golden rune is a method of harmless communication between himself and the god.
After he had input his message into the golden rune, it flashed and disappeared. This plunged the small room into darkness.
