[boastful_inaba]

In several places there's a differentiation between a "primary boycott" and a "secondary boycott".

Primary boycott: I buy from you now, but you did something bad and now I don't like you and refuse to purchase your goods/services anymore. I'm going to campaign for my friends to not buy from you either.

Secondary boycott: I don't buy from you directly, but I don't like who you work with or sell to, don't associate with them. If you don't stop my friends and I will hurt you

In some jurisdictions, secondary boycotts are illegal, usually as a measure to prevent unions applying muscle to people tangentially related to a core business.

I'm not sure of the legal status of these things in the mess of jurisdictions involved in this controversy, though.

[salawat]

Secondary boycott idn't a thing. You're thinking secondary strike, and no legally recognized Union can orchestrate one as a consequence of the Taft-Hartley Act in the United States.

This is, if I recall, the same legislation that normally outlawed "unfair" practices in Capital/Labor relations, which included making illegal blacklisting, wildcat strikes, secondary striking, retaliation, etc...