Retirements are almost always never permanent. Case in point, The Snitch. The since-retired leaker couldn't resist jumping back into the hype train to release a tease for an upcoming announcement by Sony.
Technically, The Snitch isn't the source of the leak. In their public Discord, The Snitch said that a "reliable source" has confirmed that we'll be getting more information about third-party content for the PlayStation "very soon".
Just like that, Metal Gear Solid fans have another reason to keep their ears close to the ground for the next few weeks.
Unless The Snitch is talking about an untitled PSVR 2 project, which is also possible since the upcoming VR console will come out soon, the words "3rd party stuff" for the PlayStation can only mean very few things. If we assume that it's a third-party exclusive for the PlayStation 5, it might come from one of Sony's long-time PlayStation partners, specifically, Japanese companies like Capcom, Square Enix, and Konami.