Welcome!
It's an interesting idea and I like it but I imagine if you were pitching that to the writers their next question would be "What's the story?" Scotty coming to DS9 and X happens but what is the X? When you look at how they used the TOS characters on TNG it wasn't just about them showing up and hanging out, you had Sarek with a story about alzheimers, Spock with the reunification story, and Scotty about becoming obselete. They wanted to use Chekov in Season 7 and the hook was him as a POW. I personally would loved it if he just hung out in scenes at Quarks, you saw him wandering around the Promenade, and he was basically just a background extra. I just have hard time believing the writers/producers would go for it.