So it maybe seems that the users getting Crimson for free seems to be linked to the Specialization Codes. Maybe 343/Microsoft/The Game can’t tell the difference between users with the Specialization code and users with the Limited Edition Season Passes. If that’s the case, then what if 343/Microsoft can’t fix it, and Castle and the next one end up being given free to all as well?
This could explain why getting Crimson for free only seems to be for users with the Specialization codes, and why you can only get it for free through the In-Game menu.