If the last few episodes have revealed anything about Brennan, it's that's she's not rational when it comes to Christine. This is more than her being overprotective, and it's obviously tied to the trauma she experienced as a young girl. Regardless, Christine makes Brennan unpredictable.
Maybe I’m just being paranoid but this episode felt like it was hinting at something. Brennan bringing up Max’s abandonment again. Brennan being overly concerned about Christine in general the past few episodes. Even Booth saying “I don’t want Christine to lose both parents”