4 KudoZ points awarded for this answer. Comment: "Thanks, airmailrpl. While the speaker's statement does give the impression that there might be another meaning, your suggestion that he is referring incompletely to an Achilles' heel is most likely correct. Talking with higher-ups is definitely the activist group's weak spot and the reason they feel they lose battles with people of influence. I notice that the Internet provides numerous references to "calcanhar" used as you suggest but none with other meanings that would fit in this context. Your suggestion also fits the education level of the speaker, who it seems to me tries to use some terms which he has heard but in which he may not be schooled."