Dude.....no. I've heard of condescending before, but this is just ridiculous. His line about not being an English major was clearly sarcasm (even on the internet it's plain to see) and even though you've demonstrated your knowledge and love of sarcasm with your own reply, you still managed to take what he said seriously.
Being a sophomore in college is definitely not being a kid anymore, sorry good sir. By that point, you've probably been driving for four years, able to purchase cigarettes for two years, and there's a 1 in 4 chance that you have a child. "Children" (in your eyes) often express their arguments at least as well as, if not better than, adults, from what I've seen, basing their thoughts on fact and logic. Sadly though, many adults resort to degrading the "child" by referring to them as such, especially when they've realized that they lost the argument.