This may be true in a limited number of cases. Flashing should be tested against other methods of marketing libertarianism to the general public. This is crucial. A political belief is often judged by those who hold it. One final point.
Some libertarians use the macho flash as a litmus test for potential converts.
If the listener is alienated by a controversial view, he isn't worth having. Or so these people would have us believe. It took many years for even Ayn Rand, Murray Rothbard, John Hospers, Robert Nozick and Karl Hess to become full-blown libertarians. Thought, study, discussion, persuasion and time were necessary. And these people are very intelligent.