It's amazing and bizarre that you see it like that. Logically, what OP is saying is entirely possible.
The point being made is that other games being announced today and previously, are also having press releases, multiplatform trailers and social media clarifying that these are multiplatform games.
They are having no problem also announcing PS5 with PS4, Xbox One with XSX, Steam etc across old / new gen - right now. It is premature to come to any conclusion on why PS5 is missing from this specific western release announcement, across trailers, social media and even the press release.
What OP says is entirely possible. Equally, it could be a marketing thing, could be that the game just isn't getting a PS5 version at all for some reason and they just use BC with PS4, could be PS5 doesn't launch this year so the game isn't being announced as releasing "this year" along with all other platforms - no one knows, but its a worthwhile discussion.