With regard to the concept of "sportswashing", whether it's real, what it actually amounts to (I wanted to quote someone here, but I lost track of the post, apologies for that) and so forth: I had a conversation the other day with an expert on ME politics.
Her basic point was this: sportswashing is more subtle than it's usually portrayed as. It's not about making people with "Western" values genuinely changing their stance on, say, LGBT+ issues - or about making journos stop publishing critical pieces about this and that. It's not even about making certain demographic groups (like football fans) turning a blind eye *. No, it's simply a matter of normalization, establishing a presence that people get more and more used to.
Once people on a big enough scale have become used to having you around (a high-profile presence), you don't need to worry about a) a lot of people not agreeing with your politics and b) journos writing critical pieces about you.
Bottom line: it's about normalization. Or, if you will, it's (as always) about business: normalization is good for business.
* Although this is obviously a bonus. And in the particular context of Manchester United being bought by Qatar, it's a significant one: United have hundreds of millions of (actual, active, passionate) fans across the globe. The possible effect is on a completely different scale compared to City.