I have seen very little on this item in the mainstream media. I was also disappointed that there was nothing at work on it during briefing. With that in mind I offer the following:
An IED means that it was IMPROVISED. It is made from common things that are cobbled together to make it one unit. IF he did use a CO2 cartridge, we are left to wonder how big it was. There are different sizes and types. IF he stuffed it with a gun type powder, it will burn and therefore produce some type of reaction. If the hole in the container where the fuse is placed is small, there may be an explosion instead of a propulsion. If there is any type of plea arrangement it will come in the form of getting on the plane with a homemade firework and not a bomb. However that is secondary to the fact that he did it and may only result in minor mitigation as will the relative facts about how much damage something like that could cause. The experts will weigh in on this as will the attorneys.