How does "thought-provoking dissonance" in Zen Buddhist dialectics differ from "wrong speech"?

Zen question-and-answers and talks like the ones described here don't seem like commonly accepted 'right speech'; yet, they are believed or intended to trigger spiritual progress. In what way do such Zen interactions deliver benefits? For example, are they meant to be thought-provoking dissonance, discomfort and anger, and thereby cause dissatisfaction with habitually-held positions, and thereby create scope for spiritual progress? Have the teachers specified (in any writings or talks) how to distinguish such dissonance-causing dialectics from "wrong speech" which causes hindrance in spiritual progress and delivers no spiritual benefits to listeners/readers?