fist of all Celestia is not stupid, two she will see Scootaloo is not a chicken and last she do NOT have a canon to banish other to out of the world to the moon! and to me I hate to see her be scare of Chicken, here what she really scare is a monster of can take the form of armless creature to low your guard and attack when you with his real form and is will be too late, so Celestia can see the monster in his transformation , the reason is she can see the Aura of all living creature but this creature scare because as a child trauma by see 6 royal guards be murder by this creature before Star swirl beat it. Luna is be too young to remember this, is the main she hate be alone in dark forest, some forest have those monster, Luna a learn by Star Swirl of the Trauma of her sister and is the she protect her sister against those monsters good thing for Luna to be too Young to remember the horror her sister a see. Luna a read info of those monster, only Alicorn magic or extremes level of magic like Star swirl can beat it those monster, Luna wish to cure her sister of this but is really hard, the info say ones you fear the aura of those monster is mostly impossible to be cure of it, Luna do not believe of it by the fact of living in land of magic so she really believe she can cure her sister of the effect of fear of those monster plus she ask herself why those monster take the form of a chicken most the time, report say those monster love chicken but those monster hate the sun light and moon light, or light from fire, those monster fear fire a lot, those creature will never attack someone who is close of Fire camp, this is why is lure them out of it but those creature can’t fly and you can easy escape them by hide on a tree, the monster is not really smart and his view is very limited