Like GreenBB13 pointed out, this is sportswashing: attempting to circumvent the previous icky associations most people have of Saudi Arabia - icky associations that come from small things like their horrific human rights record and a habit of sending thugs to foreign countries to brutally murder their critics - by throwing absolute shed-loads of money at people, institutions, and leagues that people like.
Saudi is, and has been, desperate to expand their influence culturally and economically because they see the writing on the wall for the future of their oil exports, so they can throw essentially unlimited amounts of money at this project. Sadly, but understandably, it seems to be working. I can't say I'd say no to a $300M payout.