Hi Sean Ellis ! Thank you for the feedback =). I agree that changes in the UI, specifically the change you're proposing, would further help manage risk. I hear that you're somewhat disappointed on this UserVoice item not being prioritized yet. To decide what features to build, votes, impact to end-user, change management, capacity, and many other factors are considered. So far we have focused on delivering more robust features for meetings and accessibility (e.g. live captions or private channels), considering that SharePoint already does quite a good helping users manage risk, and under the assumption that if Guests are allowed and added to Teams, they should have access to the information being shared (otherwise why add them?). If this continues to be important, keep the votes up, we keep monitoring it. Also, be sure to raise this ask to your Microsoft Account team if this is blocking your deployment.
Thank you for sharing your thoughts with me =)!
Nydia