The alien wasn’t a threat for the cousins because, although they initially felt fear and curiosity, the alien needed their help. When they approached him, they saw that he was injured, with one of his legs bleeding. The alien did not show any aggression but instead required their assistance. The cousins, being brave and kind, used the First Aid kit to treat the alien's injury. The alien appreciated their help and kindness, which proved that he was not a threat but simply in need of care.