First of all, it is very rare (I believe) for a family NOT to have an open casket when then are mourning the death of a loved one. The fact that there was no open casket (when every other "star" had one) screams "Something isnt right" to me. There is no religous reason as far as I know for them not to have had an open casket.
The second reason why I dont believe this story is even if you embalm a body and keep it is the refridgerator it would be decomposed after 3 months. I know I read up on that when they were trying to say that Michael's body would be prepared and make-up put on his face.
The whole funeral / burial story is weird and suspicious to me. Then of course we knew what "DAY" the funeral would wind up being - before it was ever announced because of the bloody shirt in the closet with the 3.99 price tag.