Pettis should be fighting at LW.
His whole reasoning for asking for Aldo is so he doesn't have to wait too long for his next fight. Having him fight Aldo in August doesn't make any sense for Pettis, seeing as a fight with Bendo/Melendez would be right around that time anyways. If the Aldo fight was in June, this would make sense. In August, not so much.
The UFC should just make Pettis take another fight at LW if he doesn't want to wait. The are FW(s) like KZ & Lamas that could be fighting Aldo.