Any aircraft commander who would hover a helicopter within the range of automatic rifle and rocket propelled grenade launcher risks both the aircraft and crew. Assumption of that risk to "blow down" a flag (religious or otherwise) is, quite simply an "unacceptable" action.
As a US taxpayer I do not consider the risk of losing a Blackhawk to blow down a flag anything but negilgent conduct.
It would be difficult to justify a low altitude, low airspeed hover over any possible battle position when overwhelming 'air superiority' would allow a significant reduction in risk by attacking targets from higher altitude. If the flag was a legitimate military objective I seriously doubt that any responsible commander would order it removed by helicopter downwash.
This was a lesson the US learned in Vietnam. It was a lesson the brave Russian helicopter pilots learned in Afghanistan. It was reinforced in Mogadishu with tragic loss of life by Blackhawk pilots. It has been learned again by Apache pilots in this war.
The destruciton of any flag known to be a religious object would not be tolerated in the US. Were this act committed in the US, those who perpetrated that act would face criminal charges.