Trust busting is an anti-free-market position. The freemarket consists of individuals voluntarily interacting. Any position that advocates coercion, i.e. government interference, is anti-free-market.
Trusts are a coercion, and a crime greater than a bit of government trust-busting. (Or, in really far-out versions of anarchist theory, non-government trust busting. I don't know of any real-world examples of that, though.) I do not naively believe that an economy can be run completely without coercion, but that such coercion as is necessary should be turned to keeping the market free. The optimal ideal case for free markets simply doesn't obtain everywhere. Spectrum is at least dubious; perhaps now we could just run it as a free market and it could work (people with far more knowledge about radio issues than me have argued both sides of this, I can only sit on the sidelines of that one and wave genially) but that certainly wasn't the case in the analog radio era.