[MinorityRepublican]

Not being a lawyer my take on it is not that they are not advertising on X but they are in a conspiracy to keep others from advertising.

This is the same kind of stunt Rockfeller used to pull. Although, in this case it is more political because Elon Musk isn't a Globalist.

[Miami Rebel]

Rockefeller used his dominant market position to drive out competition in the petroleum business; Morgan used his with railroads.

The advertisers are not competitors of X. They are therefore not analogous to monopolists.