I suspect they are removing Delamar because of the additional points of interest they want to add in the near-ish future. New asteroid tech, drive in and sinkhole entrances to caves, and the overall polish. They may even be closer to Crusader being a true planet you can explore, with points of interest by itself. (3.14 by the looks of it in the roadmap). From what I recall, Stanton is pretty full as a single server, and they need to remove stuff if they want to add in new POIs, outposts, etc. At least, I am hoping these are the reasons for removing it.
there is another possibility, and that is server meshing might be coming sooner than originally thought. If they can get three systems, Nyx, Pyro, and Stanton online, this would allow them to test and start major balance passes on multiple systems and gameplay loops. For instance, with Pyro bring a criminal haven, and Nyx being more neutral, especially with regards to UEE laws, you might have people wanting to do trade convoys and escort missions from Stanton to Pyro, running through Nyx. You would also have opportunities to mine ores in both Pyro and Nyx and then transport them back to Stanton for sale. This is probably further out than the first reason.