I'm in full agreement, though Mangione's manifesto illustrates that his goal was terrorism -- to make healthcare CEOs afraid. But hey! Let's also look at how health insurance companies terrorize millions upon millions of Americans day after day.
It's clear that a system which demands you pay it for 'protection' against illness or accident, then revokes that protection when it judges you unworthy through an intrinsically biased and flawed lens, is terroristic. It colours every aspect of one's life, by design. People on 'health insurance' debate whether to go to a clinic for their cough, just in case it's not covered, because they can't afford the charges.
If terrorism charges were legitimate, every insurance company would be indicted, and so would many, many others who subsist off an economy of fear. The fact that they're not illustrates the true nature of these charges: another half-baked method of control, and typically a racist one, too.