Because his/her I-485 has beeen pending for more than 180 days, the new employer does not need to do the PERM/I-140 portability because his/her green card application has nothing to do with the new employer. As long as his/her new job is in the same/similar area, his/her I-485 will be fine. If USCIS asks the job change, he/she only needs the new employer to provide a employment verfication letter and that is all. Obviously this lawyer is not professional in the immigration area. Or the lawyer just wants to get more money.