sounds like sabotage to me, if the truck ran at idle for 45 min, -anything- in a cat would burn out, I have seen too many trucks that had a seal go out in the hyd pump of a k21/k25 and filled the crankcase with hyd oil, and had oil blowing out the exhaust until they quit running and they 'self cleaned" the cats in about 20 min after the pump was fixed and oil changed to the proper levels. to get so much water as to effect the operation of the engine would require a hose shoved up the tailpipe when the engine was off and cold.
Now, if the whistle was an intake vac. leak, I can understand the truck trying to richen the mixture, and overloading the cat so it roasted, idling for that much of the time. but no water survived that.
5 minutes should be the maximum allowed time to idle, because -I- said so. (and about 178 other reasons)
but as we say around here, something in that dog just don't hunt...