Well it's true that we don't know for sure in the sense that it's certainly possible Sakurai and Famitsu are being somewhat facetious about why Lucinia was separated in the way they're saying things and what information they are choosing to include. It could possibly be the reason you just stated. But what we've actually heard from them so far seems to indicate that the reason they were separated wasn't because they are different characters. Either way it shows that at some point they were O.K. with the two sharing a slot, which says a lot. I apologize in advance for being accusatory, but I feel like you're choosing to go along with the interpretation that most fits what you want their stance on their stance on alt characters to be, rather than what makes the most sense. Which is of course fine when you're talking about what you want, but when you're debating about what the actual situation is...
As for the idea of Daisy being a Peach alt., that's a whole 'nother matter. Even going by my interpretation that it's gameplay based, them sharing a slot still depends on Sakurai thinking it's O.K. for Peach and Daisy to play exactly the same, which he might not since Peach's moveset is very feminine and Daisy is mostly a tomboy. Or he might be totally cool with that, who knows. But the issue of if what Peach has in this game can be made to fit Daisy is a whole different issue from whether or not Sakurai is ever O.K. with alts being different characters or if sharing a spot in any way implies that two characters are the same character.