Am i alone in thinking you are v. judgemental??
If you read the thread you linked to the guy has decided that the child is too young for a trailer so what's your problem??
I used one for my ds from 9 months, he could hold his head and i used an extra support thing. I cycle on roads too ().
Obviously i wouldnt be heading down a dual carriage way on it but as long as i cycle safely then i dont see a problem.
FWIW in my personal experience cars give you a much wider berth with a trailer attached than they do if you just have a child on a bike seat.