First off, it seems to me that we're dealing with her thinking that since she considers comics to be juvenile garbage that can't have any merit because she can't boast about what Mike has accomplished, they should also be beneath her. She thus is yet another irritant sucking the enjoyment out of her child's life so that she can boast about his accomplishments thereby gaining the approval of other snobby idiots.
His being a low-brow little boy who embarrasses her by not being a horrible phony isn't the only thing that she wants to save him from. After all, she's a prime sucker for quacks like Doctor Worthless who want to blame Bat-Man and the pulps for the kiddies' anti-social stupidity. It's not that Mike is being raised in a hellishly stifling environment where he is either threatened with or subjected to violence on a daily basis by self-absorbed idiots whose fragile egos can't deal with the same frustrations everyone else has to deal with; it's Bat-Man's fault for teaching them to punch people.
Finally, we're dealing with the fact that his funny books and cape and imaginative play are all getting in the way of his being a good son and admitting that he is merely an extension of their will, duty-bound to live for them and them alone. More on the ugliness that is living through the kids tomorrow.