System Admin Logged In as Standard User can still access Developer console
|Knowledge Article Number||000060503|
Developer console is available only to users with "View All" and "Author Apex" permissions. To open the Developer Console, click Your Name | Developer Console.
By default, Standard profile users do not have the "View All" and "Author Apex" perms and so, they do not have access to Developer Console. However, when a System admin logs in as Standard profile user(via Login As functionality), can access the developer console.