Edit: I will point out the obvious - you are breaking the license doing that.
The software you have already shipped with the devices is the source code you must supply to anyone who rightfully requests it.
Not some modified version of it ... so you already have the code (unless the devices have been shipped but not working?)
This is not correct.They have NO obligation to give
you the source code. They have an obligation to give the source code (indeed, the actual code and not a 'cleaned up' version) to parties that they gave the binaries to, if they request it. That's it. Go read the license.