For a player with that posseses the kind of fanbase Neymar enjoys, I understand what you mean and how his influence is going to positively affect the Saudi Pro League if he returns to playing for his club.
He only can contribute good marketing effects if he can have appearance on field in actual matches for Al-Hilal. He has big fan base but if he continues to be absent months by months because of different injuries, the club will not receive considerable marketing effects, shirt sale effects from Neymar. They invested a lot of money to this player and in return, so far we can say Al-Hilal seriously failed.
Having an injury is a bad thing for a player, no one wants to experience that, so it is a risk for a player and also the club that recruits him if something unwanted happens, no one can be blamed
By getting many injuries and many severe ones, Neymar recent years has been increasing his time with injuries, recoveries and trainings than for actual matches. No club want to pay lucrative salary to a star player who can not play for them too often. Neymar is such a player in the last two seasons since his transfer from PSG to Al-Hilal.
but Al Hilal has also received increased marketing thanks to the arrival of star player Neymar
Do you have figures to prove that Al-Hilal got benefits in marketing and income from Neymar?
I don't believe it to be honest and Neymar is under a level of Cristiano Ronaldo in fan base and marketing effects.