As far as I am aware the age labels are related to legal requirements not real life. I don't have a packet to check but just read the ingredients to check there's nothing your child shouldn't be having. I think they probably have too much sugar in for little ones so people normally start with more savoury stuff but don't know this, merely postulating .
I have bought some of those organix gingerbread biscuits and my DD didn't like them much...They don't have sugar added, but maybe the size, shape is what is not suitable for younger babies. I don't know if ginger is OK for babies either...
anyway, if he likes it I see no problem, but don't leave him unattended (which I assumme you do).
jammi, I wondered about those gingerbread men too as I bought some for DS as well as the Organix finger biscuits which are suitable from 7 months and couldn't see much difference in ingredients. Neither has any added sugar.