[artfulhippo]

Supporters and resistors of the utilitarian framing of benefits of (sub)urbanity are both being over-simplistic.

Of course we make decisions on balance of their expected outcomes. The problem is that we can't in general predict outcomes with certainty. So, intelligent decision making is not merely to pick the best expected outcome, but to factor in the range of all possible outcomes on a probabilistic basis.

In this thought experiment, it seems that city-dwelling is highly probable to benefit the disabled kid, but we have less a priori certainty that suburb life is better for the accelerated learner (it may be better for him today, but it's plausible to think that it's long-term good for a smart kid to experience some amount of adversity in a tougher environment compared to a more comfortable sheltered suburban setting, or to learn by example that it's sometimes worth risking personal optimality to serve the needs of others).

So yes, the notion that we should prioritize the needs of the bottom of social hierarchies is worth considering, but it's even more important to factor in uncertainty, to have no pretense of one's ability to predict the future.