Leftists aren't the Catholic Church. Their attempts at shaming people were effective because they already had power over people. Something we lack. We need to gain power first, and that means persuading people who don't currently support or agree with us.
By not tactically useful I mean it's counter to what I see as a useful strategy to achieve leftist ends--in other words, liberation from state and capitalist oppression. And I see mass public support as essential for achieving those ends, which means attracting many different types of people to work together to achieve these ends. And while it's certainly possible to build such a coalition without workers at defense firms, it would be easier with them. And if we add up all of the different messaging that excludes people in a similar way, it becomes a far more significant obstacle. Why would ordinary people want to join a political movement they view as preachy weirdos who harshly criticize anyone who doesn't share their exact lifestyle and worldview?
But if you feel otherwise maybe you can articulate whose behavior you think will be influenced by this kind of messaging and what you expect them to do differently after seeing it?