I'm going to just ignore anything that's not in the game because this whole "Rule the Earth" nonsense comes completely out of the left field and wasn't alluded to in never. I hated the fact that the game has no real ending and just stops, but I will take no ending over that.
The only fairness that I'm gonna give Alvarez on this point is that it's kind of in vogue for creators to retroactively edit their work via interviews and Twitter.
For instance, there's little if anything in Harry Potter to suggest that Dumbledore is gay (or that he even has a sex drive at all), but according to JK Rowling (in interviews she conducted YEARS AFTER Deathly Hallows), he and Grindewald were totally doing it in the butt back when Dumbledore was young and bishonen. There's virtually nothing in the books to support or back up these claims, and it was just something Rowling came up with because (to her at least) it was a politically correct thing to do. It didn't add to or improve the story, it was just something she felt she could tack on after the fact. It's worthy of note that there aren't any revised versions of the books that include this detail either, so it's a plot point that exists SOLELY in late night tv interviews and social media posts. Yet, because Rowling said it, fans were expected to take it as canon, and many do.
What Alvarez did here was no different. He retroactively introduced a plot point after the fact via social media despite the fact that there was nothing in game to support that conclusion -- and in fact, quite a lot to actively oppose it, given that the
whole story revolves around Dracula trying to cease to be the sort of person who would take over the world. On TV Tropes, we refer to this sort of stuff as
Word of God, and it's a concept anathema to
Death of the Author, which basically states that the author should not offer interpretations of their own work, or, alternately, that their interpretations of anything not directly stated in the work are no more or less canonical than any given reader's interpretations.
I tend to support Death of the Author because Word of God is lazy writing like releasing a blatantly unfinished game and then patching it to completion after everyone has already beaten it is lazy game development.
Basically, if it's not directly supported by existing canon, I treat it as noncanon, or at the very most, an interesting fan theory by the author.
Alvarez and Rowling (or any other creator for that matter) can make all the claims they want, but until they make a defined work that directly addresses the point in question in some way, their interpretation is no more or less valid than yours or mine.