1. Counterexample: if I were to become an arms dealer I should have more money with which to educate my children.

It is not narcissistic to give nonzero weight to the greater good. Inevitably one attempts to achieve that by implementing the conception of the greater good to which one subscribes.

2. The author strictly speaking isn’t doing what you call narcissistic, and doesn’t seem to be advocating that either. What is noted is that the result of many parents’ seemingly individually innocuous actions is an overall injustice. The author does not send the child to the worst school mentioned and does not therefore prioritise “ideology” over children. Moreover the author is not saying that this is the obviously correct course of action to take. It is merely noted that to take this course of action is part of a collectively regrettable pattern.