The response itself tells you alot if you put a bit of thought into it.
Most people don't care about disclosing their age unless they feel that it would damage them in some way (older people hanging out in teen areas, extremely young people hanging out where they shouldn't be, etc), based on his posting style, attention starvation, and various other things I've noted since he's been posting, I would place money on him being pre-driving age where he lives. Most likely he is older than 11 and has started puberty already but has not gotten through it, so my standing guess would be 14.
Shadus