According to the Encyclopedia of Bible Difficulties p.362, the Greek here, epi Abiathar archiereos, simply means "in the time of Abiathar the high priest". Abiathar was not only alive then, he was present when this occurred.
Neno la kigiriki, epi Abiathar archiereos, linamaanisha "wakatii wa Abiathari kuhani mkuu." Si tu kwamba Abiathari alikuwa hai wakati huo bali pia alikuwepo jambo hili lilipotokea.