Tong Shuwen played a good hand.
His way of thinking was indeed correct, who would expect that Xian Yu was actually a singer about to debut, but couldn't sing because of his damaged vocal cords and thus reluctantly turned to composing, with enormous success as a result?
As for whether losing the competition would affect Xian Yu's position as a judge...
There is even less to worry about with that.
Here, you can make an incomplete but appropriate analogy:
The relationship between a composer and a singer is like that between a screenwriter and an actor.
You say that a screenwriter and an actor compete in acting, and if the screenwriter loses, does that mean he is not qualified to judge the actor?
There's no such rule.
Plus, Xian Yu's relationship with his collaborating singers is probably not just that of a screenwriter and an actor, but also that of a director and an actor.
Think about it.