To advise a child not to read a comic book works only if you can explain to them your reasons.
Supposing you get used to eating sandwiches made with very strong seasonings, with onions and peppers and highly spiced mustard. You will lose your taste for simple bread and butter and for finer food. The same is true of reading strong comic books. If later on you want to read a good novel it may describe how a young boy and girl sit together and watch the rain falling. They talk about themselves and the pages of the book describe what their innermost little thoughts are. This is what is called literature. But you will never be able to appreciate that if in comic-book fashion you expect that at any minute someone will appear and pitch both of them out of the window.
....In this case the girl understood, and the advice worked.