I prefer to think of Aesthetic as a less rational, more monkey-brain part of us. A lot of the things we find beautiful come from basic instincts of what is good/bad for our survival and reproduction. Healthy food, safe places, good partners, etc.
I would rationalize that finding suffering ugly is in a similar vein as finding skin boils ugly; they’re indicators of diseases, unsafe land, unsafe conditions, bad things et al.
Going with the “people’s suffering” take, perhaps wanting to act on immediate, in-your-eyes suffering is an aesthetic choice/preference, but making a (shut up and multiply) decision wouldn’t be aesthetic, but fully rational? Our monkey-brains can’t quite grasp the people’s suffering continents away from us, or imagine the actual amount of people suffering, so wanting to act on that as a whole wouldn’t touch on our direct aesthetics, but in conscious, controlled rational thoughts.