That's not how it works. If there's interest in a union in a company, the employees have the right to make the case for it, and then they vote on it. Sounds like the company in the OP tried to quash that right. Why do owners have the sole right to determine whether a company should undertake that experiment or not?

And beyond the legal and moral implications, you still haven't addressed my core critique: Silicon Valley tech startups claim they can change the world and disrupt everything. Yet when it comes to the subject of labor relations, they default to some sort of Victorian Era fear of workingman unions. There's an inherent fear that unions are unworkable and malevolent. That just completely clashes with tech's belief in its infinite innovation. Even if past unions didn't work in America, why be so afraid of building a new one?