Exactly. Anything, and I mean anything, can be argued for with whataboutism because we live in a world that's corrupt to its core and has been since records began - every authority we've ever known be it governmental, religious, economic has proven itself completely untrustworthy and so we either stay in this perennial loop of self destructive caveman logic or we don't. Personally I know my actions (should Qatar, or any state, come in and buy United and I stop following the team) won't make a difference but I'll be doing it anyway because it's what I believe is right.
I've seen people called 'holier than though' for saying similar on here but it's just a different opinion and the most vocal and vociferous posters arguing for this seem like they are trying desperately to justify it to themselves as ok. We all know it's not ok, we all know it's completely against the values that the club tries to represent and was built on so it shouldn't be surprising some fans aren't happy with it. If you decide you can live with it and just want to see the team win, each to their own.