Song Zichen isn't the best at approaching anyone - even if he recognizes them. However Wei Wuxian is a special case and since they are in another world entirely, he wants to do what he can for the man. Surely he is a new arrival?

When he is close enough, he gives the man a deep bow, his gaze flicking between the ground and Wei Wuxian's face.

"It's good to see you again."

And since Song Zichen is clearly alive and able to speak, that should the other some information about what he has experienced thus far.