Graphus doesn't 'manage' users, contacts, domains, groups, etc. It only views them. But the APIs provided by Google include both the capabilities i.e. view and manage in the same API.
For example; Graphus integrates with Contacts API and this contains API calls for both; 'view' and 'manage'. The same is the case for all other APIs.
Because of this Google is explicit in outlining all the capabilities that are being allowed.