We didn't fail to support the event. We rejected the event emphatically. It was a right-wing event.
The general message is not remotely the same. There is a difference between organizing workers in an imperial country where all non-explicitly-communist institutions are reactionary to some degree, and organizing with the fascists self-consciously responsible for making it that way. If you're genuinely confused about that, you have a lot of reading to do, because even the democrats are better at recognizing their enemies.
The libertarian party is both fringe, and the most ideologically anti-worker organization in the US. It's impossible to be further away from union organizing. You think they want to end the war and spend that money on healthcare for workers? They are literally repealing child labor laws. Some of them think slavery should be legalized.