I always find it funny when people make the excuse of "Well I ignore all these other bad things, so I couldn't possibly start changing my mind now". Talk about mental gymnastics, why not begin to take a stand for a glaring example like the Saudi royal family, and work from there?
Not caring about the football club you love being owned by literal monsters(who persecute people on a daily basis), for the sake of some new players and the possibility of trophies, is cretinous behaviour. Don't try and make yourself feel ok about it with whubbery.