I think Al-Hilal's goal in signing Neymar is not only to strengthen the squad but they want to cooperate commercially with Neymar. We know that it can be said that Neymar's influence is third after Ronaldo and Messi in football, therefore they want to continue promoting the saudi league with the star players they have managed to bring in. Neymar will definitely be very happy to be able to help the Saudi league and he will also contribute his experience in Europe for development here. Regarding Neymar's injury, this is nothing new for Neymar and indeed we can only hope for a faster recovery.
It could be like that, but what is certain is that Neymar was declared to have suffered a minor injury. it is possible that he has not actually recovered from his injury. or it could be, if Neymar was injured in the pre-season match even though Neymar scored 2 goals in that match. and my assumption is that Al Hilal knew very well about Neymar's condition before they brought him to Saudi. in fact, the coach Al Hilal stated it during the welcoming ceremony for Neymar. that the Brazilian star will not be making his debut any time soon, probably in mid-september. roughly, that's the rumor I read.
If we examine it, it means that Al Hilal already knows Neymar's condition but they don't seem to mind it. after all, if it's only a minor injury, maybe Neymar only needs one or two weeks to return to the field to make his debut with his new squad. and in any case, the presence of neymar for Al Hilal will have a positive impact. and as you said, Neymar is not only to strengthen the team but there are other contracts that involve commercial matters.