I think it's completely fine to be extremely skeptical of, and yes even outright mock, the idea that sitting for 6 hours a day does permanent, irreparable damage to the body until proven otherwise. It's also probably fine to be skeptical-bordering-on-mocking of people who use sources that sound authoritative to push something controversial. It's really hard to become a cardiologist. They know a great deal about a lot of things, but you know what they typically don't know anything about? Exercise. They're not physical therapists, they're not exercise physiologists, they don't have PhDs in kinesiology.
Sitting is bad for you, sure. But some random guy's random cardiologist friend likely knows less about exercise science than a $50/hr personal trainer at your local Gold's.
Of course they care. Every tourist killed brings more attention to them than needed, if the person was high profile enough it can bring enough international pressure for the government to take them down.
