Most big 3rd party publishers get a big portion -in many cases half or even more- of their AAA revenue selling games/DLC/IAP on PlayStation, something explained with the install base market share. So I assume it's the same in the case of Zenimax. So I highly doubt they will reject all this huge amount of revenue just to make happy some fanboys, because as a company they will want to recoup the investment they did on Zenimax as fast as possible in some years and to get a positive ROI.
On top of that MS is already losing a ton of money almost giving away 1st and 3rd party games day one on Game Pass, and as Game Pass grows their revenue from 1st party sales on Xbox and PC will keep decreasing because even if a small portion of players will continue buying some of their favorite games on physical even if they already have them on Game Pass, the majority of Game Pass users won't. So until Game Pass grows until a critical mass that allows them to turn it into a profitable business,, if it even achives its, they will want to have a good alternative revenue sources, and the main Zenimax one, or at least a huge one, should be as of now to sell games on PlayStation.
The Disney and Fox deal has nothing to do with Microsoft and Zenimax. Microsoft isn't a market leader in gaming, they are the 3rd one behind Sony and Nintendo. Even addiing Zenimax revenue/market share. There are over 1500 million games sold for PS4 and way under 10% of them are from Zenimax, so won't have an impact on PS4/PS5 Sony 3rd party game sales (their main revenue source). So to remove Zenimax games from PlayStation would be a dumb move that would have basically no effect on the Xbox vs PlayStation competition, it only would mean tons of less revenue for Microsoft and to make a few fanboys happy.
Fox catalog of movies and IPs is way bigger than the Zenimax one, and unlike Zenimax has a substantial market share so means a huge move in the market because now combining Disney and Fox they are a clear market leader of the box office, that's why they paid 10 times more for Fox than for Zenimax:
In 2023, Disney alone accounted for over one-quarter (20.3 percent) of the box office revenue in the United States and Canada, thanks to blockbusters such as "Oppenheimer".
www.statista.com
So in their case, being Disney a clear market leader and having tons of top movies and IPs that give them revenue from many sources and not being Netflix the main one at all, makes sense for Disney to avoid Netflix and co because Netflix is a small part of the revenue that Fox made, unlike it happens with Zenimax, for who PlayStation was their top, or one of their top, revenue source. For Disney, having Fox movies on Disney Plus and not in Neflix will mean to make more money than before while at the same time earn market share and crush a bit more their competitiors (in this case Netflix & co). For Microsoft, to have Zenimax games in Xbox and not in PlayStation would mean to make less money than before beause they already had them on Xbox and made most of their money on PlayStation where Zenimax had a tiny market share of the total games sold in PlayStation, while Fox's main revenue source wasn't Netflix and Fox catalog was more important for Netflix.