I think most of us knew Frank would be found in the water. It's human nature for families to wonder if his death was due to foul play. Mainly I believe it's a safey mechanism that gives them some reassurance that they were not responsible for his disappearance.
The reality is that young children always seem to have a fascination with things that can be so incredibly dangerous. And when bad things happen it's hard to reconcile that fact. I think the fascination comes from seemingly benign things when viewed as every day items.
Little kids take baths, they see their moms turn on the tap to wash the dishes or to boil spaghetti, so when they see water outside; ponds full of fish, flotsam caught on branches over a river, rushing by making lots of noise they are drawn to it, without being able to parse whether in this iteration water can be deadly. The same can be said of fire. Little kids sit around campfires roasting marshmallows or see their dads burning leaves and don't associate themselves lighting matches under the sheets as grave danger.
I feel sad that Frank is gone and hope he died swiftly and without pain. Little kids don't understand death, at that age they are like a deer who has no prescience in regards to running across a busy highway means death.
This case reminds me of Dylan Ehler who went missing from his grandmother's back yard in May of 2020. Her backyard borders a brook, a bit of a misnomer if you ask me, since it feeds into the Bay of Fundy which has the highest tides in the world. In May, the 'brook' was very high with spring runoff. The search and rescue team recreated the disappearance using a mannequin the same size and weight of Dylan and they believe his body was washed out to the bay. No closure for those parents.