I would also like to say that it is my opinion that the pineapple is not really relevant to this case.
I believe that JBR ate some kind of vegetable matter with the crab, could be lettuce or lemon fibres, or some such.
When Arndt was at the house she saw a bowl of pineapple and noted this. When she was at the autopsy Meyer commented to her that there was some kind of vegetable matter present and Arndt asked if it could have been pineapple.
Thus an urban legend was born. That is my opinion.
M