Players wouldn't be enjoying Starfield this September if the game was coming out on PS5 according to Pete Hines during the ongoing Microsoft Activision FTC case.
Starfield has been at the forefront of arguments against the Microsoft Activision deal. While a huge noise has been made about the possibility of Call of Duty going exclusive, Microsoft denies that would be the case. The fact that Starfield will only be on Xbox after Microsoft bought Bethesda has players doubting Microsoft's word (well Redfall too, but in hindsight, I think PlayStation owners are quite happy they didn't get that).
However, Bethesda's head of publishing Pete Hines took to the stands and claimed (via transcription from Derek Strickland) that Starfield "would not be coming out in 9 weeks if we were supporting an entirely different platform". Hines also stated that having the game exclusive to one platform "has been a big benefit to that team". Interestingly, Hine's also stated that a single platform approach for streamlining development is "literally the reason why I recommended exclusivity" for Deathloop, which was announced as a PS5 exclusive before the Microsoft and Bethesda deal was announced, and had a one-year exclusivity window on PS5.
It belongs in a museum
Pete Hines also went into some details about the upcoming Indiana Jones game from Machine Games, claiming that "After the acquisition, Disney brought up the issue of which platforms it would be brought on". Hines finally gave confirmation that Indiana Jones would be exclusive to Xbox platforms (which should've been a given, considering Disney also let Marvel's Spider-Man be exclusive to PlayStation but some players still weren't sure).
Even then, based on Deathloop and Ghostwire: Tokyo's PS5 exclusivity, there's a chance the game would've been locked to one system at launch anyway, considering there were rumours that Sony was angling to have Starfield as a PS5 exclusive from games journalist Imran Kahn (via GameInformer), and that seems even more likely to have been the case after Hines' comments about Deathloop's exclusivity.
Obviously, it's a bummer for players who can only afford one console, but I'm not shocked by the comments coming from Hines during this case. Considering almost every Bethesda Game Studios title has been littered with bugs at launch, maybe this is an angel in disguise for Starfield. Microsoft needs a big win after years of lacklustre exclusives, and if this acquisition has given Starfield the chance to be the best game it possibly can be, maybe that's a good thing.