Can't blame him at all.
Yes he's probably got a year still left at the top level in Europe, but he's really getting up there in age. He's probably feeling it in his body at this stage. He'll know the full situation of how he's feeling, it's not like it's something he probably would have done years ago. It's time to cash out and play an easy standard of football. A big reason he'll be getting such a lucrative offer is his current standing. If you go elsewhere in Europe and fade away you're not quite the draw to the Saudis.