My own announcements do not change the credibility of any threats available to agents seeking to exploit me.

They inflluence the liklihood of them being made in the first place - by influencing the attacker's expected payoffs. Especially if it appears as though you were being sincere. Your comment didn't look much like signalling. I mean, it doesn't seem terribly likely that someone would deliberately publicly signal that they are more likely than unnamed others to capitulate if threatened with an attempt at extortion.

Credibly signalling resistance to extortion is non-trivial. Most compelling would be some kind of authenticated public track record of active resistance.