Surely not all that blood is on the hands of the CEO, or even UHC. But everyone has either been denied claims or knows someone that has, through some of the most disgusting treatment witnessable from corporate america. It'd be one thing if you were denied a claim for.... any variety of reasons that follow from the inherent difficulty of managing health insurance as many countries can attest to. But overriding doctor concerns to withhold funding for necessary treatment and withholding as much as possible while raking in profits leaves people with very bitter tastes in their mouths.
Mine included: I'm paying for a medical procedure for a friend next week because her insurance won't cover anesthesia and she can't afford the out of pocket. I had multiple relatives die much sooner than they had to because they were denied funding for critical medication. I've had multiple friends talk about "rationing insulin" (thankfully, both times referring to the past). And naturally healthcare interests—UHC included—lobby both parties heavily, so there's a lot of incentive to continue ignoring the elephant in the room.