It is not forced to spend that is the issue, the group pressured other organizations to NOT spend money on advertising, pretty much the definition of a trust.
The scope of antitrust laws, are to insure a organization or group of organizations do not interfere via monopolistic practices in an enterprise’s freedom to conduct business, and to protect smaller businesses, communities and consumers.
A group structured prevent others from using a service that can benefit materially from that harassment qualifies as a trust.
“...pretty much the definition of a trust....”
In NO way is that the definition of a trust, and I defy you to prove otherwise. The only way anti-trust would have any bearing would be if the alternative advertising mediums coalesced to suppress X either by saying, “If you advertise with them you cannot advertise with us,” of if they slashed ad rates in a concerted fashion to undercut X’s rates.
Obviously this is ludicrous because (a) there are THOUSANDS of alternative mediums and (b) it isn’t an alternative medium that is being sued but rather the advertisers themselves.
This would be as if Bud Lite chose to sue not the people calling for its boycott but rather the customers who stopped buying their six-packs.
People campaigning for boycotts of ANY product are free to do so, and those who listen to them are free to stop buying the boycotted product.
“It is not forced to spend that is the issue, the group pressured other organizations to NOT spend money on advertising, pretty much the definition of a trust.”
Similar, I suppose, to companies colluding for price-fixing.