Read the ATF regulations carefully and you will see that they require separate storage of _detonators_ but no mention of igniters.
This ruling does require that the storage be in compliance with local law. My local fire code says that storage and use of rocket motors will comply with NFPA 1122, 1125, and 1127. NFPA 1127 has a provision stating that reload kits will not be opened until you are ready to use them. (4.5.7) So opening the package to remove the igniter would put me in non-compliance with the local code.
I am not sure why the ATF has a problem with this. Most display fireworks are now shipped from the factory with an e-match installed in the lift charge. So there are many tons of explosives currently stored in the US that have an "igniter" not only in the same magazine but in close contact with the explosive. If this were a serious problem, fireworks magazines would be blowing up on a very regular basis. They aren't.
David Erbas-White wrote: