It's the platform's responsibility to properly sandbox apps. It should not allow apps to intercept emergency calls under any circumstances. Alternatively, you

It's the platform's responsibility to properly sandbox apps. It should not allow apps to intercept emergency calls under any circumstances. Alternatively, you could have a completely open platform, and then the onus is on Microsoft Teams and the user--but neither Android nor iPhone are like that; both choose to sandbox apps by default. When I install an app on a Pixel that isn't rooted, I expect that Android will keep it from intercepting 911.