Al Hilal are well aware that Neymar was injured before they decided to sign him. They should be aware that they were not buying a perfect player after Man City, Chelsea, Bayern, and Real Madrid, deliberately turned down the opportunity to sign him. The striker should enjoy his fat pay and the club should build on the reputation and experience Neymar will bring to the team.
If Al Hilal was aware of this, then it is fine. Otherwise it doesn't make any sense to spend so much money on him. Injury has been a big issue for Neymar. He is still regarded as one of the top-5 footballers at present, but there is not much demand since he is prone to injuries. But a few good matches can turn the tide for Neymar. He has the quality, and the opposition is not that tough. And one thing we need to remember here is that Neymar was purchased not just for his skills, but also for his celebrity status. And who knows? He may play an important role in the 2030 World Cup hosting bid by Saudi Arabia.