I think the point is more that many kinds of software (presumably including aerospace software) doesn't really need any kinds of protections from redistribution because it is effectively only useful for a specific design and much of the effort in creating it is not the algorithms that a competitor could steal without copyright or alternative protection but certifying that the software fits the rest of the system, which any competitor making use of the software would have to do again.

Also remember that the original point of copyright and patent protections is to encourage people to create the protected works in the first place but Boeing isn't just going to stop making aerospace software without copyright because their hardware will be useless without it. So if anything, any software that is needed for hardware made by the same company to function doesn't really have any right to be copyrightable at all.