I don't see the problem with stalling the FW division. The FW division needs to be stalled because there aren't any true contenders after Florian. Aldo can defend his LW belt while the FW division catches up in the meantime and produces a contender every now and then. Even if Aldo only defended his FW belt once in and defended his LW belt 3 times over the course of the year, that would be good enough because the FW division doesnt have any challengers to offer and four fights in one year is not overwhelming or too taxing.
It would be great for the UFC on multiple fronts. First, the UFC could hype the shit out of Aldo and make him a superstar by marketing him as the first double champion in history. Second, this newfound stardom would garner more interest and legitimacy in the featherweight division, which would not only make more fans care about the lighter guys but also make more fighters compete in the FW division which would in turn help it grow and produce more contenders.
Aldo can become MMA's answer to Pacquiao: a foreign lightweight with crazy speed and striking who holds belts in multiple weight classes and draws big attention to the lighter fighters.