Would a sprinkler proved valuable had they been sleeping or away absolutely. But here is a classic case where a sprinkler would not save a life just like smoking in bed. But of course none of the sprinkler advocacy groups mention how many times you can die from a fire in your home and the sprinkler system will not help.
Often times there are fires which are low heat and slow burning and a sprinkler will never respond. a Fire Marshal I know was called to investigate a trailer fire which everything from outside looked perfect yet inside every wall was burnt and consumed from just such a low heat slow spread fire. Sprinklers are just one of the chain of times needed to protect.