When an admin creates a new query that query is set to Active. No criteria is required. They can then assign that query to a device group which can have many assignments already attached to the group. This WILL return every device in DB and populate those assignments.
If Queries by default are set to Inactive on creation then this will reduce unexpected behavior. Do not allow "Empty" queries to be saved/assigned which will also help protect admins that do not understand these default behaviors.