Mushoku Tensei: Jobless Reincarnation

[KrayZ33]

I don't know about all that but "need" is certainly not "it would be cool if he had stayed".
That's my point.

Ruijerd right now would be completely depending on Rudy (UNTIL something happens where he can help which might not even in the next 20 years), not the other way around.
Not something an adult should do to a kid, especially if you consider what Rudy will try to do if Ruijerd is around. He won't look out for his own or himself, he would try to help Ruijerd first and foremost whenever possible and make the rescue of his mother/sylphie a secondary objective (as he cannot do anyhing but "travel")