Do you think KJ was speaking in terms of how he wanted the story to unfold. In theory, maybe it can be stopped, but as a storytelling device, it was unstoppable because he would never want to "cheat" the viewers in that way. In "Hulk Breaks Vegas", the hulk-in started, but was interrupted when the Hulk got shot in the arm. The sudden pain caused him to "re-hulk" (hey, I invented a new word!smiley: laugh) So, if a Hulk-in can be 'switched' to a Hulk-out, why couldn't the converse be true?