While I hesitate to presume any logic on the part of government agencies, I don’t see a problem. I would assume the answer is that the specific facts of each individual case are considered, rather than applying a blanket “all mergers are bad/good”.
Net Neutrality: impinges on profits of big telecoms.
Sinclair: amazing opportunity to simultaneously reward a major republican donor and disseminate overtly biased, conservative talking points in millions of American homes.
ATT: great opportunity to kneecap CNN, which the President hates.
There is little to no truly balanced and fact-oriented media. Obviously, except for those perceived as such by their respective viewers on either side of the political spectrum.
BBC (UK), PBS (US), NPR (US), ABC (Australia) etc are surely examples.