OP is misleading. He’s saying it won’t be exclusive to PS6 at launch, not that it won’t be exclusive to PS5 at launch. It’s very likely they have a timed exclusivity contract with Sony.
Is it tho? And at this point who cares? The messaging and optics around the game just makes it sound like they really don't want it as a timed exclusive anyway so if that's the case, why pay for timed exclusivity?
Everything coming out of these guys' mouths feels like a wink in support of "certain" anti-exclusivity narratives that aren't even true (i.e Jamboree, Astro Bot, Helldivers 2 if you're just talking among console releases etc.). Clear there's a reason they keep messaging this way; do what you want as a 3P but just come right out and say it. Enough with the ambiguous talk.
SIE are probably better off using that money on their own 1P game development and marketing instead. Let Square-Enix handle their own development and marketing, if they think they can do it on their own.