Is it neccessary to have a pending I-485 for EAD renewal?
So you're saying that he cannot renew EAD if he cannot file I-485 (because of retrogression).
Not only can he not renew his EAD, but his current EAD automatically became invalid once his I-485 was denied. This assumes that his current EAD was a C(9) category (based on a pending adjustment of status case).
His problem is not retrogression, since if he's eligible for 245i he has a current priority date. His problem is that if the original I-485 was denied and his old sponsor no longer wants to hire him, he has no basis to file an I-485.
I don't think he is still eligible for 245i since he's no longer connected with his old sponsor.