It's not so much that they thought they had to lie about the pineapple itself. They had to lie about her not being awake and not seen alive again. They had to lie because that pineapple was eaten about 2 hours before she died. It would NOT appear partially digested in her small intesting if she had eaten it at the White's or before going to the White's. It would have passed further along her digestive tract by that time, possibly even been excreted.
The pineapple in her stomach took them by surprise. They had no idea it would be found in an autopsy, let alone in an identifiable form. At the awful moment they realized what they had done- where the pineapple she had recently eaten would be in her digestive tract was NOT among their realizations. And if it ever HAD been they would assume, as most people without a background in forensic medicine, that it would be digested and unrecognizable. And the bowl had only PRs prints. They HAD to deny knowledge of it. It pointed right to PR.
Why is the timing important? The closer the murder to the time they arrived home (say, death occuring midnight-1am as opposed to 4 am) the less likely it is that an intruder commited the crime. JR and BR were up a while playing with a toy. By PR's own admission, she was up for a while doing last-minute things for the trip. How would an intruder know where to hide? There were presents in the basement, maybe PR needed to bring them along...who knows what rooms she'd be going in? Even in a big house like that, with parents up and about no intruder would risk walking around the house. First JBRs room (to kidnap her) with a sibling right down the hall, the kitchen (to feed her pineapple) the basement (to molest/kill and stage the crime).
Sadly all the pieces fit one way. The arrive home around 10. They are all awake. JBR, while she has been readied for bed, has a pineapple snack between 10 pm and midnight, given by PR, possibly after BR goes to bed. The rage/abuse occur around midnight or so. Scream is heard by neighbor. Strange lights are seen in kitchen by neighbor (as the Rs move around with a flashlight so no one sees in the windows. )There were no shades pulled down in the kitchen- PR had short valences on the window. People could see right in, at night with lights on inside.
Cororner confirms pineapple was eaten about 2 hours before death. Rs put Dec.25th date of death on gravestone. Both are correct.
The midnight time frame fits perfectly with Patsy and JonBenet's nightly routine of a midnight potty run too.
Thanks for taking time to post your view on the pineapple.