No, they are tricking people. The same way Microsoft's trying to "trick" people to pay for BO3 by omitting Game Pass from being mentioned directly in the marketing.
SIE officially have this "case-by-case" policy on record for their PC ports, and they word it that way to be intentional ambiguous and put doubt in people's mind if a game will come to PC. Meanwhile, their actions this gen have been them porting basically all of their titles from 2020-onward to PC in increasingly shorter windows.
So then you have someone one the Astro Bot team a few weeks ago say they can't picture the game on other platforms because of how "uniquely PlayStation" it is, or whatever that's supposed to mean, and just a few weeks later up to its PS5 release they're basically teasing the PC crowd for a potential port? Maybe SIE and other companies think a lot of other people have the memory of goldfishes, but I'm not one of 'em.
If they weren't trying to trick people to maximize their revenue at the expense of potential customers doing what's best for their own wallet, they'd just outright go "hey, this is releasing on PS5 at launch, but we'll have a PC version in the near future. Stay tuned for more information.". But they aren't doing that, because they're worried some of those Day 1 paypigs will just wait to get the game on Steam where SIE makes less money....but the only ones forcing SIE to put it there in the first place are themselves (and maybe Sony Corp higher-ups)!
Me personally, it's not about the game being on more or less platforms, although I don't think there's anything stopping someone from getting a PlayStation to play a game that's just on that platform, and the game being a real exclusive isn't "anti-consumer" in any way whatsoever. If you don't have the money to get the system for the games, get a side gig. Really, what it's about is if a company's going to put their games out on multiple platforms in due time and I don't naturally have FOMO to play the game at launch, don't try to force FOMO by acting like the game'll be exclusive one place, only to turn around and announce a port a few months later.
If you're playing on multiple platforms anyway, chances are you'd just like to buy the game once, preferably where you think it'll play best. And since SIE have been doing this PC strategy, often times the best place to play their games is on a PC (if your setup is good enough). If the game's good enough and brings enough hype on its own merits, you'll still get a ton of Day 1 sales on the console anyway....
....right?