Iran might not have that but Russia does. And it's not just reverse engineering that we are talking about here, having this drone almost intact would allow extensive RCS studies and experiments to be conducted, testing different radar wavelengths against it for instance. Ultimately it contains valuable info that could be used for stealth and anti-stealth research. This aircraft is not an empty shell, a shape only, it's also materials, it's electronics, sensors, etc. It's not a secret that the US are ahead of everybody in UAV technology, that's why for countries currently developing such this drone would be a gold mine.