A couple comments:
- FSA in DC became unionized before I retired. As a manager, it was another pain, another hoop to work through. But it wasn't really that big of a deal, as I remember it. My suspicion is that the union has become less effective over the years because of turnover in its members, meaning the original members who pushed to get the vote have retired and/or got tired. That's the way humans do. (Might be wrong, particularly as issues like Trump's attitude towards civil servants and more importantly Perdue's proposals for reorganization have come to the fore.)
- As I've been distracted by working on a book for a relative I've not read the decision or evern detailed discussion of it. But, not allowing that to stop me, I'd think the principles of the decision spell trouble for the agricultural marketing order/promotion system. I'd think the argument is the same: being required to pay fees to a union or promotion fees to a promotion organization is a violation of free speech and free association.
That's not to say I like the fact. While sometimes I lean libertarian I do think the government can appropriately encourage the formation of groups, like unions and marketing groups.