Again, mixed messages. Your symbolism is just tradition and doesn't really mean that, until it does.
Talking about how unions are for everyone and not about antagonism while adopting clearly antagonist symbolism while trying to take both sides simultaneously really sends the messages: A) we're cosplaying rebellion because we think it's cool and B) we're the ones starting the antagonistic relationship.
This is the problem with supporting unions rationally. They are sometimes necessary in certain industries and situations but also full of people who want to cosplay rebellion and grab power so they can abuse it instead of someone else.
Adopting a fist raised in defiance is definitely a way to attract cosplayers and repel support from everyone but the extreme. Particularly when your message loud and clear is "unions are for everyone not just those in trouble".