He is technically correct but reality would say that the employer would want the ATPL subjects done so they know that you won't be a permanent FO.
You can use your CPL to do other jobs. Para dropping, glider towing, fire spotting (perhaps not the UK!!!), instructing (with the rating), scenics.... basicly any flying (within insurance and legal reasons) that doesn't require 2 crew. You will probably need more hours to do Air Taxi but it's a start.