Reason #3: Both artists would have something to prove if they were given the chance to work extensively on Aaliyah's posthumous project.
Let's face it: Timbaland isn't considered the hottest producer in the game anymore, and Missy isn't considered the most well-respected female MC in the game, either. So, if they worked on Aaliyah's project, they wouldn't just be out to prove that Aaliyah was the greatest female singer of her era. They'd also be out to prove that they were a big reason she was so successful. That kind of motivation could make for some great music.