The silver pine tree is an entirely new material and previously unseen species. This kind of achievement made the sect promise to do everything they could to help Thor reach the nascent soul.
So if Thor doesn't care about the rat race to the top involving other disciples of the sect, it is because he has the right not to care.
Arthur had a little part to play in the project, but his contribution is minimal. He only improved on the previous version. The idea and execution were all done by Thor.
His help is why Thor decided to meet him. Thor doesn't meet just about anyone. He is too busy to meet with people. Only a golden core sect elder can meet him by force.
After talking about the silver pine tree for a while, Arthur got to the main purpose of his visit.
He asked, "Do you know a material that can isolate mana, insulate lightning, and is durable enough not to be destroyed by lightning?"
Thor whistled and said, "You're asking for a unicorn."
Arthur sighed and said, "I know."
