The common complaint here is that the signalled motive is usually wonderful and altruistic - in this case SAVING THE WORLD for everyone. Whereas the signalling motive is usually selfish (SHOWING YOU CARE, being a hero, selflessly warning others of the danger - etc).

So - if the signalling theory is accepted - people are less likely to believe there is altruism underlying the signal any more (because there isn't any). It will seem fake - the mere appearance of altruism.

The signalling theory is unlikely to appeal to those sending the signals. It wakes up their audience, and reduces the impact of the signal.