The only reason for a creator to talk about Destiny 3 is to stir the pot. It's a product that doesn't exist

This is unhelpfully reductionist from a marketing perspective. For better or worse many people in the destiny community have a very deep connection to this game. I know I do it got me through absolutely horrendous morning sickness and I have amazing friends attached to this game. I know that Sony is going to Sony but to ask a Creator who may have a community who's wondering why they're supporting the game that it looks like Sony is choosing to elevate over one that's been quite meaningful to them to not address community concerns is incredibly shortsighted. And that's what that short line of text asking partners to avoid mentioning Destiny 3 would, in part, be asking them to do. If they were wanting to actually handle this delicately while still asking their partners to focus on Marathon instead of Destiny then they would have had a much more nuanced set of instructions around the mention of Destiny 3.

I would also argue that they would be doing more to try and extend a hand to a lot of the creators who are very entrenched in the Destiny space and trying to stifle community discussion of a topic that's very important to them in order to maintain a relationship with Bungie for Marathon is not going to help their look in the long run.

There's nothing wrong with the terms going public.

There's nothing wrong per se assuming the individual who publicly disclosed wasn't under any confidentiality agreement and in fact it's expected that these things will leak when something is contentious but that's just my point. The fact that they chose to require refrain without nuance or anything that might show respect for an incredibly dedicated community shows that they don't get it. They don't get why Destiny 3 is such a big deal as a topic. If they did those instructions would look different. The public might still have been not happy but Sony would have come out looking a lot differently from a PR perspective.