True, enough, but there are and should be rules to govern such situations. If one is in immediate danger, then they are no longer snipers, but mortal combatants...
If the enemy threat were a goat giving cover to an enemy combatant, the sniper would be fully justified (and expected) to first take out the goat, then the enemy combatant, then anything else that popped up offering hostile restiance.
You see, the idea is not to die for your country, but to MAKE THE OTHER SOB die for his.
We have won two World Wars with that philosophy and it works just as good today as the day Adolph Hitler killed himself while hiding like a rat in a hole because American fighting men were bent on one thing and one thing only - KILLING THE ENEMY.