Honestly I still don't quite understand why would a guy like Geoff Johns have so much value to the point where the DC Films President would allegedly want to convince Fisher to get off his back. Over the past years we've seen anyone from actors, directors, producers and CEOs get fired or blacklisted, people with much more value to movie studios than someone like Johns could ever have, so why would WB want so desperately to keep some comic book writer? Yeah, he basically created the modern DC landscape, so what? They don't need him as a consultant for adapting stories that he wrote, they don't need him to write or produce movies or shows about Wonder Woman and Green Lantern, they don't need him to consult on Black Adam just because he made him an anti-heroic character during his JSA run, they can easily replace him with another showrunner for Stargirl, just like they replaced that former Arrowverse showrunner who was fired after allegations of misconduct. Johns is every bit as replaceable as anyone WB has ever employed before, so what makes him stand out in all of this?
I said this before, the only people I would feel sorry for if he gets booted are his creative partners for his comics. People like Gary Frank and Jason Fabok don't deserve to have their books potentially canceled after working their asses off on them for years.
I'm not a fan of Johns for the record, so I'm just playing Devil's Advocate, but here's the thing: Johns has been with DC for 20 years. He has experience in television, film, comics and knows everything there is to know about these characters/brands. He has plenty of connections, he has plenty of fans (hell, he's probably their biggest "name" exec), he's currently a producer on several of their upcoming projects, and he has plenty of people in all 3 industries who who have him to thank for their careers, so he's surely got some loyalty there. And like you say, he's pretty much responsible for the modern DC landscape. That's not a "so what" to the people whose livelihoods that landscape represents. Also, film executives are typically entertainment lawyers or have business/marketing backgrounds - people with his kind of experience on the creative side and exec/producing side are extremely rare commodities - he's basically the closest thing DC has to a Kevin Feige. Aside from creating and running
Stargirl, which has been very well-received, he was heavily involved with (and co-wrote)
Aquaman, their most financially successful film in recent memory, and is heavily involved with their other winning franchise,
Wonder Woman. He's not just some interchangeable CW showrunner. He's a huge name anyone knows, with a long track record of (mostly) success with DC characters/IP's. Take off any Snyder-bias goggles about the whole JL debacle which was, frankly, A LOT of people's faults, and...Johns is likely seen as a pretty vital asset to their whole operation at this stage.
In other words, Geoff Johns has a lot of clout, both with fans and within the industry, which he's built over decades. If I'm WB and looking at this pragmatically - between Geoff Johns and Ray Fisher, an up-and-comer with few credits to his name that hasn't proven to be any kind of draw...the one who seems more "replaceable" in this scenario? Unfortunately, that's Fisher. Unless Johns proves to be more of a liability. But it will take more than vague accusations (that as far as we know include no criminal misconduct) from one actor for that to become the scenario.