Is there a way for an admin user to only view the status of the job in the list but could not change it once the job is completed ?

Answer: In the User groups currently there are no permissions that relates you to have the ability to only view the status but not change it.

 

If you are trying to block the status change once Order is Completed as an alternative you can organize or create a new list let's say for Order Completed and in the list manager you can have the list view (Filter by Status) to only show the completed status by highlighting that particular status.

 

Once created then what you can do is just have the column added that says "Status Name" not the Status in the list.