But clearly they are not the same characters. It's a throw back man. Simons theme is purely for the fans. So no one else will give a shit.
This.
And they don't have to explain anything to anyone. It's clearly a throwback and for the fans. People new to the series will come to appreciate it later. Just because his theme is in it doesn't mean he has to be in it. Just because a movie has orchestrated music in it doesn't mean the orchestra has to show up somewhere in the movie. That logic is kind of flawed.
I do love Simon's theme, but Vampire Killer will always make me blush like a school girl/red herring.
The two time lines don't need to connect or relate other than Belmonts want to kick Drac's ass anytime he shows up. Don't get me wrong, I'd love a future CV with Simon, but at the same time I don't need it. I want them to take as long as they need to perfect the lore, the story, and especially the music and gameplay.