Congrats on a job well done! I don't know why those steering shaft couplings are so hard to remove. I have to remove on eon my ML350 and it took A LOT of impact force both to separate it and put it back in place. I even tried to pry the slot on it open more for the re-installation and that did not help much.
I am still amazed that the starter replacement on the M271 I-4 engine is such a chore. I've done them on the V8's and V6's in W203, W209, and R230 chassis and it's quite simple - unbolt it and drop it out.