I don't see how they turn this down. Their main goal continues to push consoles. Their main competitor in the high-end space is MS. If they're willing to put their games on PS platforms through Game Pass, even with it being streaming, that's beneficial to Sony just like it is tot hem. Because from Sony's perspective you can still play the next Naughty Dog, Sony Santa Monica, Polyphony etc. game on your PS4/5, but now you'll also be able to stream the next HALO, Forza and Gears. And MS obviously gets the wide net of users that PS consoles have.
Sony's main goal isn't to simply push consoles though. It's to connect gamer to creator and take a slice of the transactions between them. The console is just a means to that end.
If they carte blanche 'allow' a competing streaming platform onto their devices, they're enabling another middleman to stand between the user and the creator that isn't them.
If Sony allowed gamepass on PS hardware, I think it would most likely be for MS first party content only. They won't let MS dis-intermediate them with regard to other third party content Sony is themselves offering access to via their own services/platform. Yes, MS could offer a revenue share, but Sony ultimately wants that third party content being engaged with through their ecosystem/platform and to take the full platform-holder cut for themselves, not share it with MS. So I think they'd let gamepass operate as a third party publisher offering within their own ecosystem, but not as a fully-fledged ecosystem in its own right, competing with PS services for access to 'multi plat' third party games.
So I could see Gamepass on PS in the same way I could see EA Access on PS - as a gateway to content belonging to MS and EA only. I don't think Sony will allow them to use those services to serve up third party content that Sony wants to serve themselves to you. From the Jeux Video rumour it sounds like in the Nintendo case - if that's true - Nintendo will also be curating what content is exposed on their device. If that's true my guess is they'll probably also only allow stuff they're not competing for access to on their own platform.