Sentence:  Because he spoke openly with what Channing had prophesied someone might - with daring hyperbole - Parker vindicated Channing 's further prophecy that he who <WSD>committed</WSD> this infraction of taste would promptly discover how little mercy liberals were disposed to allow to libertarians who appeared to them libertines . 
Meaning of the word marked with <WSD> tags:  perform an act, usually with a negative connotation