It wasn't the higher ups who shot down the romance between Spidey x Ms. Marvel. It was Dan Slott who put a stop to it the moment he became the head writer for Spider-Man. He even said that if he had wrote the Spider-Date, he would reveal that the person that Carol was dating is a Skull impersonating as Peter Parker. Besides, if Slott had decided to explore their relationship, it would not be very good under his penmanship. I feel that the best way to protect the fans interest with Spider-Man and Ms. Marvel is to keep their relationship at the "PALS" level and increase the number of heroines interested in Spider-Man to Spider-Woman, Psylocke, Silver Sable, Black Widow, She-Hulk, and Ms. Marvel. All of them respectively would serve as an alternate to the Black Cat as Spidey's partner in a guest spot. And the list of heroines mentioned is to give a Spider-Man writer a choice as to which heroine he wants to pick of the six alternate to use in his stories.