Let's be honest, many very demanding games released on Series S on day one, yes it's too unpowered, yes it asks more efforts but all devs do it, why not them?
They just didn't prioritize the Xbox versions, I mean you think game dev at this level is what ? 3 dudes in a garage scratching their balls with one hand and the other hand on the keyboard ? They've to be organized, the Series S is 3 years old, its "weakness" isn't new, and even them are saying they'll be able to achieve it with time, which means that if they started the dev on Series S earlier, the game would have released on Xbox on day one.
But of course they have the rights to prioritize the PC version, or PS5 version or anything they want, but then it's on them, not that much on Xbox.