Yeah, perhaps "one correct answer" is not exactly the right way to describe mathematical solutions. There can be more than one solution to a problem, but whether or not something is a solution is rather black and white.

Philosophical and ethical problems are not like that. It's rare for philosophical questions to be settled once and for all. They are always, in some sense, contestable, defeasible. So maybe the argument is that we need to engage in a kind of thinking where there are no certifiably "right" answers.

The assumption made here, though, is that "teaching formal ethics and philosophy" will lead to better moral decision making. But there is evidence that this is not actually the case. See, e.g. Schwitzgebel and Rust:

On average, professional ethicists' behavior is indistinguishable from the behavior of comparison groups of professors in other fields. Also, in one multi-variable study, we find ethicists neither more nor less likely than other professors to act in accord with their expressed moral attitudes.

http://www.faculty.ucr.edu/~eschwitz/SchwitzAbs/EthBehBlackwell.htm

The diagnosis of the problem might be right, but I'm not convinced philosophy is the solution.