Moderators will not see the external email in SSO section anymore via:
https://github.com/discourse/discourse/commit/59a8471308634685fe882fb393ce6d48dba7d2c6
If moderators do need to check user email for investigation purposes they can always click on the 
Show button next to Email (provided that moderators_view_emails setting is enabled).
Hiding the external email (in SSO section) behind the button for an Admin will require significant more effort, will add to my nice-to-have list.