> But this is so obviously someone falsifying these reports—to be a troll or to make United Healthcare look bad or whatever

It is entirely believable that UHC is working with some crisis management firm to try to manage public perception, and that part of their strategy is to try to get media portraying Mangione positively taken off the internet, whether or not they have legal grounds to do so.

There have been so many past stories about companies using illegitimate DMCA claims that I'm surprised you consider it obviously not UHC or someone working with them. It is possible, but I don't think it's a forgone conclusion.