There's a difference between a boycott and threats of violence.
One, a boycott is not inherently a crime. I could choose to boycott, oh, say, Wal-mart, and if I announce I am boycotting Wal-mart, it doesn't necessarily follow that this boycott is illegal (because it isn't), or that if I follow through on boycotting, that I have committed an illegal act.
Whereas, if someone threatens violence, depending on jurisdiction, it IS a crime. (In some states, threatening others with the intent to cause harm is considered assault. Actually harming them is a separate crime.)
Now, consider the following:
1) A statement by a group that if Wal-Mart is open on Thanksgiving Day, the group will boycott Wal-Mart for the duration of the Christmas season.
2) A statement by a group that if Wal-Mart is open on Thanksgiving Day, the group has threatened to attack Wal-Mart employees.
The first is a boycott. The second is a crime.
Class is dismissed.