I could see this being useful. Not everyone who uses a wheel chair is paralyzed. Some have balance issues, or limited strength. Dividing the effort between arms and legs could give increased independence and it would be more ergonomic than scooting with the feet like a lot of people end up doing in wheel chairs.
Sure, it's not super different from a recumbent bike (and seems to lack a steering mechanism) but if the pedals could be folded out of the way it could be easier for a person with mobility issues to get in and out of.