Transylvania 2 not for kids

I've just taken my 18 month old son to see Hotel Transylvania 2. He absolutely loved Hotel Transylvania 1, and has watched it many times. He was in a state of high excitement to be going to see this movie. Imagine our surprise (shock) when we were told that the Publications Control Board have rated this as nobody under 7! My son is now in tears. This is an animated kid's movie and, even though he was accompanied by me and his granny he was not permitted entry. What happened to our constitutional rights? Who gave these people the right to impose their views on the rest of us? He can go into a bookstore and can grab a porno mag off the shelf, but he can't see an animated movie. I would really like to understand their reasoning as I'm just flabbergasted right now.