That's the basic idea.
So all of the core guard posts are spread around the core worlds and stuff. This is, ideally, with the same basic density you see on the homeworld. So, overall, there are far more guard posts. However, a set of the guard posts will be linked like the prime core shield generators are. Those are your real objectives. You kill all but one of them, and the last one dies. The guard post that is the 'prime' set is determined on worldgen, so you could get Core Laser Posts that are linked like prime shield gens, or Core Missile Posts that are, or so on. The rest of the guard posts are still present, but are all linked to the same type of guard post like the secondary shield gens are. So, if you find one completely unbeatable defense from one angle, you approach from another angle and take down one set of secondary guard posts by killing just one of them. That peels off that layer of guard posts, and makes other angles of approach easier. Once you've softened the planet up enough, you take out the remaining prime posts, and then the homeworld is vulnerable as normal.
As for what to do with brutal posts, I was thinking leave them on the homeworld. I don't know if they actually protect the home command station. They should definitely stay on the homeworld, since splitting up the guard posts like this is done to make sure you always have some kind of viable angle of attack. Perhaps, as a second phase, the brutal post(s) can remain on the homeworld and protect the homeworld until manually destroyed. Then, well, all you have left is home command.