According to dictionary.com:
Child - noun, plural chil·dren
1. a person between birth and full growth; a boy or girl: books for children.
According to American Heritage Dictionary:
n. pl. chil·dren
1. a. A person between birth and puberty.
b. A person who has not attained maturity or the age of legal majority.
According to WordNet 3.0
1. a young person of either sex; "she writes books for children"
The defining trait of all children is age. Child does not, however, mean a loud, irrational, destructive person with poor communication skills.
If you use "child" as a synonym for the above, you're using it incorrectly. Just as a misogynist who uses "woman" to mean something other than "an adult female person" is wrong.
EG is a fucking champ in that thread, btw.
You're uncomfortable around children? Fine. Own that. It's about you and whatever issues/perspectives you have. Making it about some supposedly "objective" assessment of children's behavior turns it into "children deserve my dislike--it's not me, it's them." And the assessments used are almost always assessments that can equally apply to adults.