You're telling me that Dialga and Palkia aren't gonna be in SV because SwSh's returning legends were exclusively Gen 1, some random left-field picks and the ones from the most recent games?
I'm saying that SWSH didn't have all, or even most ("exclusively gen 1" equating to 9 of the 35 pokemon, and of those we only had 2 of the 5 gen 1 legendary/mythic pokemon) of the legendary Pokemon. I suspect those foreign weirdos were mostly (though not all, I also suspect the kanto starters & mewtwo were always planned for Pokemon Day stuff) a hold over from earlier in development, or had different plans in mind at some point at the very least.
I do not think SV will either, because they will inevitably just bring them back in full as a selling point later on. They're almost certainly going to stick with dexit as an active plan so why bother doing anything other than the bare minimum marked out? They can always do the development later alongside the other things they're going to add later.
I mean it could be there
I can't fully prove it, I guess. No one can until the games are out. Maybe every single legendary will be there, maybe it will just be all the restricted pokemon, maybe it will literally be Zacian, Zamazenta, Dialga & Palkia and no one else!
But also maybe they just won't, you know?
Anyway regardless of all that, I don't see them throwing out all the Home plans they are clearly working on as a...."selling point" for SV. The selling point is already the fact that Home is the only transfer method that eveyr game has to deal with and that LA & BDSP & SWSH will have their own mutually exclusive Pokemon to send forward without leaning on Bank.