Originally Posted by moicanorj
If you not kill them so instead you are killing the people that they will kill in the future
What people? The area was deserted. Lee's group were the first people they had seen in ages.
There is no way they would have survived the walkers, Their defenses were down, the generator was out, Andy could barely walk and Danny couldn't walk at all. They were sitting ducks and would have been torn to shreds. You didn't need to see it to know it happened just like you didn't need to see the bandits rape and kill Joleen's daughter. Based on the principles of the walking dead it's implied and considered inevitable.