Ok pls write 100 times on the blackboard "I wont attack with the slow, weak and useless granger anymore"
Grangers are slow, they have really poor dmg, and humans love to kill them. Thats 3 reasons for not using granger in battle.
Just because you managed to killed a very noobish player, or more probably a guy already badly wounded by others aliens with a lucky shot at the right time doesnt mean you are useful.