You are correct. So often when humans try to intervene, the situation worsens. I believe the bison calf should have been left along.
But I find it the ultimate irony that the National Park Service, who would condemn a tourist for upsetting the cycle of nature plays around with nature all the time, like introducing super predator wolves in Yellowstone and other parks and those wolves in turn decimate the ungulate (hoofed animals) population in those areas. Elk, deer, moose and antelope have all seen a precipitous decline in population in the mountain west states.
The NPS should live by the same rules they would impose on the rest of us.
Mother nature is Mother nature. The National Park Service is the bloated federal government.
The latter can never be the former, except in the minds of liberals.