no you didn't make that up, you did read that cos i wrote it. my friend, who is a paediatrician at A&E as well as a father, told me 'if in doubt avoid red until a year old' when i was going to give DD some raspberries. he said that he wouldn't be giving his dd tomatoes, for example, until she was a year old.
so i have taken his advice when i've been in doubt and when it's been easy for me to do so (so about as unscientifically as it's possible to be). for example, dd hasn't had rasps or strawbs yet, but that's cos this summer there were plenty of peaches and i prefer them as much as anything else. also, she has had cooked tomatoes in sauce but until recently i didn't give her fresh tomatoes. again, no science behind it, really.
i believe he is ultra ultra cautious because he sees little babies with allergic reactions being blue-lighted into his work. there are some people from very allergicky families who might avoid tomatoes but i found it pretty inconvenient and so i caved almost immediately.
so there you go, i wrote it, and i did write it in exactly this context rather than as a 'rule' but it seems that the only bit that stuck in your memory was my friend's quote.... so i've learned a lesson and will be more careful about repeating it in future.