The FTC is notorious in healthcare for causing trouble among hospital organizations that want to merge. Occasionally over the years, and depending on the political affiliation of the administration in charge, the agency would get serious about its role as an arbiter of fair trade.
As such, the FTC would choose to challenge hospital and health system acquisitions that it felt would cause a monopoly over healthcare services in a given geographical area. Never mind the expense that would be associated with dissolving a partnership. Of course, no one wants a hospital to dominate a single market and exercise monopoly power, but the agency certainly isn't as vigilant on the payer side of the equation.
Frankly, an FTC challenge, for hospitals at many times in the past, was simply an annoyance. It might delay the transaction, but seldom did the agency ever ultimately prevail in preventing any but the most obviously anticompetitive mergers from happening. It's much more than an annoyance now. The FTC's actions may seem arbitrary, but this Bumble now has teeth, and it may be best to try to avoid him until things get a little more clear, or until an elf with a proclivity for dentistry comes along.