I did the another the application last year and never booked the assessment for ATP. Not seen many people on this thread mention getting a job through ATP, if at all in recent years and thought it would be a waste of money to pay to do tests and 7K for another MCC / JOC.
Not sure if they do the same selection tests as the cadet. If they do, its almost insulting if someone has all the licenses, has been flying public transport in GA or very experienced commercial flying instructors.