You made a good point about Laniet's gurgling on a different thread, but transposing it onto Sheila Caffell is a stretch too far. Gurgling, the death rattle or other noises emanating from the corpse is the final toll of mortality, but it doesn't enable someone to have sufficient energy to pull the trigger of a .22 rifle for the second time.
It's a possibility, but since Dr Vanezis could not rule out SC pulling the trigger a second time, which often happens with suicides, its largely irrelevant.