Earlier quoted context omitted.
Yes, exactly. And it’s underhanded and illegal when employers do it, because there’s an imbalance of power between employee and employee. Unions exist to even out that balance of power. When employers engage in that kind of activity it further increases the imbalance of power. For example, in this case, they were using that tactic to support their ability to steal from employees.
To clarify this further: The employer is already a collective, "A business", and the hiring manager is operating with the full power of that collective in hiring/firing negotations. A union is a collective to balance power against the business (collective). A cartel is a collective of collectives (ie., a group of businesses) operating to defeat free market competition regulation, in this sense the cartel is balancing…
If they're good or bad is another matter.