A terrorist is someone who enacts violence against civilians in order to create political change. Not saying Luigi deserves any of this, but if his goal was to make a point to the world about the mistreatment of patients at the hands of insurance companies in order to push change, then the terrorism charge is accurate.
What insurance companies do is far worse than terrorism. They harvest the sick, elderly, and injured for their money in order to sate the capitalist urge to increase revenue for the investors. But that isn't illegal.
It's not harder to cancel than to sign up though. It's a one or 2 clock process to cancel and a whole lot of card details entering to sign up.