HiFi Rush on PS5 only makes sense to me if something else is going on behind the scenes.
Like that sort of suggested move - tip-toe-ing out back catalog games - I'd have previously taken that as a sign that there was some movement on the idea of GamePass availability on another platform. Even early talks. Some change, at least, in the path MS sees from where we are now to that point.
It doesn't make sense as a revenue grab to appease MS Corp and their big investments - a relatively tiny little critical darling? It makes more sense as a baby-steps, strategic exploration of something else, some kind of business relationship, while execs talk about other things.
I know MS and Sony relations are supposed to be at an all time low, but you could look at Ryan's departure and add a further 'hmm' to the mix, if you wanted to add some colour to this tales-from-my-ass speculation ;)
But seriously, it would be very strange in isolation, and would make me wonder what else might be going on.