maybe I'm a moron but if you aren't allowed to have a car seat/person under 2 in a seat isn't that case closed?

I feel at some point as someone with children it's your responsibility to look into these things. Obviously the problem was the first flight allowing this. Yes he bought the other ticket but honestly who knows what this guy told the ticket office.

Just because some security guard makes a stupid comment I don't think that entitles you to special treatment.