I know it's not the same as onscreen Trek, but two at least Trek novels from the last decade have included the "fuck". It's been a while, but if I remember correctly one was an Enterprise novel where one of the characters was explaining that WTF meant What The Fuck? and in one of Vanguard books a non Starfleet character says "fuck the Prime Directive" before he goes to rescue some people being attacked by Klingons. So we already have a bit of evidence that the people at CBS don't have a problem with that kind of language in Star Trek.
Actually a lot of panicky people are suggesting otherwise on social media. Conspiracy theories and the evil empire CBS sticking it to the beloved Fuller, when it doesn't seem that way to me at all.
RAMA
Where's the stuff about not being able to comment in social issues on Discovery come from? I haven't heard that before, but it's pretty what I had been assuming happened. It came down to either American Gods and Discovery, and he chose the former. I was amazed he was going to try to do both at once, so I was not at all surprised when he stepped away from Discovery.What available evidence exactly? CBS' announcement about Fuller (himself) stepping back (and not getting fired)? CBS' announcement about Fuller remaining as executive producer? Or perhaps Fuller's interview about him choosing American Gods over Star Trek Discovery? Because Discovery wouldn't let him comment enough on social issues? Which available evidence and public announcements support your theory about Fuller "not being up to it" exactly? Because everything available to us right now actually contradicts you.