Add Widget permission or block system information widget for certain users.

System Information widget is not affected by host restrictions for users.
So any user that has access to this widget will be able to see the whole picture.

almost same output for super admin and user without any host permissions:

There is workaround in 6.0 to restrict dashboard creation using roles and deny access to dashboards, containing that widget.

Consider adding widget based restrictions or at least possibility to deny system info.