I'm with you on the theory, up until your last statements - the vote to unionize was 46 to 37; 55% in favor with no breakdown in the roles means we can't be sure the dissenting voice wasn't the development staff.
It could be the support and community management roles (or any other 'soft skill' role which is less scalable and no less valuable but perceived as more easily replaced) carried the vote.
It is also worth noting that NY is not a right to work state. This means that the 37 people who voted against the union have no right to not-pay-dues to the union.
If the workers change their mind then, in theory, they will have the opportunity to vote to decertify the union, later in their employment (a minimum of 3 years). Approximately 0 unions a year are decertified this way in the US.
It's not really that big of a problem. In an ideal situation, sure, the union could represent union members and the non-union member would be banned from receiving any benefits bargained for by the union. Unfortunately, if the union has to represent everyone then everyone should pay, which isn't much different than if the <1% in leadership positions at a company makes a dumb decision costing the company money and people their jobs, the entire company is forced to follow the decision and totally uninvolved workers pay the consequences for it. At least in a union, the workers have say in how it operates and what its goals are.
There are 3 options. Non members can free ride, they can pay an agency fee, or they can pay full union dues. The Beck decision (not always well enforced) says that union members have a right not to pay for union costs outside of the agency fee.
They aren't required to, but they have the legal right to insist on it and most unions do. The concern is that, if you choose not to represent everyone, the non-union employees can negotiate better deals than you and they'll still benefit from many kinds of working condition improvements you might want.
"...support and community management roles..." are less scalable? Does this mean companies are finding it more difficult to fill community management roles than developer roles? Also, what do you mean by "no less valuable"? I don't think you can have a company who's product is software without developers. You do not, however need community managers. You make an interesting point: I do wonder if those in "soft skill" roles perceive their roles as equally valuable as software developers. I personally do not.
Support and community management are less scalable in the sense that the relationship between user interactions and time needed from staff is fairly linear. Each one is therefore less valuable, but collectively (no pun intended) essential when there are other, hungrier alternatives.
At it's current stage of maturity, the Kickstarter platform needs maintainers (SREs, Security, etc.) and staff to interact with creators and backers. I don't know to what degree new features or efficiencies will help Kickstarter become more profitable on 5% than it has been since 2010 - the product is essentially the same.
Hmm... If I worked as customer support at Tesla, I would not expect to be compensated, or frankly valued the same as say an electrical engineer at Tesla. And really, isn't community management just another word for customer support?
It could be the support and community management roles (or any other 'soft skill' role which is less scalable and no less valuable but perceived as more easily replaced) carried the vote.