EB-1A approved, Visa number available, I-485/I-765/I-131 filed

Hi All,
My I-140 was approved in April 2019 under EB-1A category. My priority date of June 2014 was ported from my earlier EB-2 petition. Visa number was immediately available so I filed I-485, I-765, I-131 for myself and my H-4 wife and son. We all went through the biometrics appointment in June 2019 and are now awaiting the EAD and advance parole card. My son who is currently in second year in an undergraduate program at a university here, will turn 21 in October 2019 and thus will not be eligible for H-4 extension. It is my understanding that his age locked in on the date the visa numers became available so he will not age out. My questions is that if he does not get his EAD before he turns 21 can he continue studying and staying in USA as "Pending Adjustment Of Status"? Any and all insight is highly appreciated.