I kind of like the idea of mixing up the guard posts more, because it is pretty jarring that the AI has these super powerful posts that it doesn't bother to use to defend stuff like advanced factories that you'd think it would care about.
That said, it shouldn't be every CSG ring. The E network for example tends to be on low priority low interest planets, and having random core guard posts there would just be odd. Plus I've seen E CSGs spawn VERY close to my homeworld, and you really don't want a core guard post next door at the start of the game when you probably can't deal with it.
It'd make a lot more sense for the A network, since those are on advanced research systems, and possibly B,C,D, which tend to be on some other high priority things. Perhaps one core non-brutal post that protects the command station (which in turn protects the CSG since you have to take the system to destroy it). Maybe even only give it a chance to spawn one so it's something that you only see occasionally.
IMO sticking the brutal posts randomly around the map would just be going overboard.