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

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...