It seems the only restriction on use of the app to administer my network is proximity to equipment and the password on the wireless network. That's not enough. After all, you offer a password on the web-based interface, just like every other router I've owned. Trusting someone to be on my network is different than trusting him or her to administer it. Thanks for considering.
@john-slattery when you set up AmpliFi, it asks you to choose an administrator password. You've selected to reuse use the Wi-Fi password for that. I think it can be changed in the app.