I really do agree it's critical thinking, but it's even even more moral values/laws/schemes ingrained in an individual, that may use maths like a tool, not pure maths that solve the moral problem.

It's easy to prove, because you may consider other criteria than the number as the age, the gender, the weakness, the social "utility", according to your moral internal scheme (moral values).

This article decide you will always use the number to decide, but it is totally wrong, one can save 5 children and let the adult to drown, because it's their moral value, or save 5 people because they are of their family. Or even from their ethnicity. Or because their moral value is "to help weak people first", they could try to save disabled people first, or save the guy who is a doctor, an artist, a politician, etc...

There are a lot of possibilities because there are a lot of moral schemes guiding the logical decision of a person, and they could take several different "logical" paths according to their own logics.

Of course, if you ask the solution of this problem with disembodied people that are only imaginary silhouettes, people will use the pure logics, the mathematical one, but in real situations, where the people to saved are "embodied" and real, the moral choices can be different.

So, it is a really big simplification, It's really simplistic to consider maths alone, detached from the internal moral schemes (that have more weight than theorical pure logics) the main determiner for moral choices.

Pure maths can also lead to decisions that would be judged as really non moral in some cultures or situations (culture: people with common moral schemes), if used as a pure tool, like the villain in movies deciding to sacrifice some lives for the good of a greater amount of individual.

If this article was true, and mathematical really so important as a pure tool for chosing moral decisions, nobody would frown upon having some economic slaves for exemple for the great good of more people than there are slaves or exploiting ethnic minorities.

Maths are really not a moral tool, especially if taken alone, as the article tries to suggest.