He might react to it, but I don't think its going to disadvantage him to not have it at home.
My boys are 4 and 19 months and we are just over 2 months Primal. In that time there was a pre-school thing, and there was cakes and stuff (made with spelt flour, and not white sugar, more like honey or something) all over the table and both gorged themselves as it was right there, and I wasn't able to distract them with what I bought.
My oldest is now saying no to things now because he knows they have flour, a 6 year old would likely do the same. But I have since that day realised I can't be worried about events like this, as they don't happen often, and as they get older they will choose the right things for themselves, we can only do what we can to educate them.