Possibly so. Still, people spend money for tickets to those performances and tend to resent this sort of buffoonery. There should be a uniform plan to counter these protesters wherever they pop up... but it has to be something that both humiliates them and amuses the audience.
Those old-school seltzer bottles might be a good choice (a~la The Three Stooges). Hose 'em down and laugh at them.
definitely never heard of Dale Carnegie...