I don't think the main mystery and classification is about the craft itself but about the cargoes and missions it takes. It probably could be outfitted to act as a rescue craft for 1-2 astronauts though in a pinch all you really need is a way to strap the astronauts in and the pack from their space suits for some short term life support (or maybe even just a CO2 scrubber pack and an oxygen bottle if the interior is already thermally managed enough for the astronaut to survive) being much smaller than the shuttle it can land at more places so they wouldn't have to be in the craft long.