Under the scenario described, at least if a twin can't keep you out of the water OEI then it can help you get on the water safely, and once you're safely on the water there might be the option of an extended water taxi to get you to the beach or closer to a rescue boat or offshore platform. Of course it depends on the sea state prevailing at the time, and whether your passengers have made an instinctive exit as soon as the waves start lapping at their feet, but at least it's an option available to you that you don't have in a single.