LOL!
I havent seen the picture of this lady (if it happened in the first place), but if she's a walking JELLO monster then its possible her fat bellybutton got sucked in and because of her inmense weight she was unable to "pull out". Maybe a flap of her fat got sucked inside the tube mwahaha.
If she wasnt obese, then her bellybutton may have slipped inside the bowl during the suction and she may have had 1 of her hips (or both, ive seen some reaaally narrow hips) "dunked" inside and she was trapped.
Either way, its something I wouldnt dream of suing an airline for. The jury would be laughing their assess off, not to mention becoming internationally known as "she who's bellybutton got stuck in the 747's toilet for 7 hours".