This is a good quote. One similar way to state it is by using the System 1 / System 2 [1] terminology. Manipulation is when someone pushes the audience to System 1 reasoning, diverting them from using System 2.
It's not a perfect distinction (there probably are cases where appealing to System 2 might look a lot like manipulation), but it's succinct, ends-neutral and not too subjective to be useful in practice.
This is only true if you assume that System 2 is always better. But if someone has rationalized great cruelty, it is perfectly appropriate to appeal to their emotions if it will get them to stop (this is essentially equivalent to a point the author of the original piece makes).
Rationalizing is very different from actually making a rational decision, and is part of System 1 thinking.
Post hoc, ergo propter hoc.
A rational decision starts with defining the epistemic system in which it is made. Is it bayesian, frequentist, higher order fuzzy logic? How the weighting, if any, works? What is the data/proposition acquisition algorithm? Which heuristics are to be used to simplify decision and why?
Rationalization can mean rationalizing a system 1 decision. It can also just mean justifying a bad decision using explicit reasons, which is the sense in which I mean it.
It's not a perfect distinction (there probably are cases where appealing to System 2 might look a lot like manipulation), but it's succinct, ends-neutral and not too subjective to be useful in practice.
[1] https://en.wikipedia.org/wiki/Dual_process_theory#Dual-proce...