Before the invention of formula this was ok to do , it was expectable and the reason its not now is because breasts are sexual objects and there is formula now. I do think if anyone finds breastfeeding weird because of a child age is weird itself. They are for humans to feed off just like cows, goats and even dogs feed their young. from a babies birth and before people seem to have a problem with breastfeeding so its on a whole this scale not just older children. I get jaws hitting the floor because I breastfeed an 18 month old and get asked why I dont give him a bottle and formula, why should I? its just to please people who have a problem with it when mum and child dont.
I see no problem with this, mum and child are happy it is expectable in my eyes,. If there was a group going about who found formula feeding unacceptable at any age there would be a bigger up roar. Something thats done for thousands of years seems to be renown less about now than something that was created 100 years ago thats more excepted.