Yes, It is allowed to mark "Active" by default.
Cello offers 3 ways of creating Tenants in the system, They are
By Self Registration Portal
By Administration Portal
By default, When the tenants get created using Administration portal the status will be marked as "Active" where as when a tenant is created using Self Service Portal the status of the tenant will be marked as "Inactive". This behavior is configurable depending upon the requirement of the product.
To change the behavior, navigate to TenantSelfRegistrationController.cs in the Controllers folder of the Web Application(Refer the below screenshot).