Caylee has not been pronounced dead.
It has not been accepted as fact by a jury of Casey's peers.
And the family has not accepted it as fact at this point.
If my husband was missing, and I either truly held out a shred of hope that he was alive or was apparantly mentally unstable and unable/unwilling to accept it and a non family member had a memorial, not a vigil or prayer gathering, for my spouse you would get very unflattering video of me as well.
I think it is in poor taste at a very emotional point in the case and accomplishes nothing. It is not bringing peace to anyone. It is upsetting the family and the searchers by pouring gas on the fire. Which brings more attention, more cameras, and more interviews.