"...they suspected that employing nouns (“I am in favour of the removal of settlers”), rather than verbs (“I am in favour of removing settlers”), to convey support for policy positions would have a calming effect."

This article is pretty frustrating. Another reason for this effect, and one I've always thought true, is that using nouns in English is often more circuitous, using more "fillers" like prepositions to convey the same idea, thus softening or obfuscating the harshness of the meaning communicated.

In other words, they don't seem to prove that nouns cause this effect, but that English's use of nouns causes this effect.