Considering SAFE is a grassroots, education-based nonprofit, they will have future needs for growth and sustainability. Choosing Firebase was a way to ensure that scaling for the internal app would be smooth and efficient even if I'm not working with SAFE in a full-time capacity when the needs arise.
The second determining factor was the ease of implementation. I am not a seasoned React Native developer, so the fact that Firebase has authentication, realtime syncing database, and security ruling built-in made it the optimal choice.