Perhaps Trump is doing this for petty reasons, but this is a good thing. Media is absurdly over-concentrated already, and should not be more so.
The only thing that would better would be a law straight up forbidding media companies to grow beyond a certain size, and forcefully breaking the firms back down to that size.
Of course, Trump’s administration doesn’t want that. The FCC is removing restrictions on ownership controls in local markets, for example.
Nonetheless, this is a good news, and we can hope that in time it will be seen to be the start of a new wave of anti-trust cases and law. The US, and the world, needs few things more desperately.