I do not believe for a single second that real (or even fictional) history/examples should justify how a game works. The goal is to be fun, not stick to reality.
About the actual plot of the discussion, I generally agree with the OP, but also I'd feel bad for someone if they lost their status as system architect if due to real life reasons they couldn't complete some specific conditions to retain their status.
Here's a suggestion :
If a player isn't active for a specific amount of time, they start losing their system architect status on their least developed system(s). IMO if a system has a lot of stations/settlements, then I don't see a reason to do anything about it. If at any point they come back, and they manually ask for their status back (maybe require a minimum level of activity first or smth, idk), then they get it back. Also if someone knows they won't be able to play for a long period of time, give them the possibility to "give away" their systems manually ?
edit: "Losing" or "giving away" a system shouldn't be seen as a negative thing, the game is ongoing, so is its story, and I think it would fit the general idea of a dynamic universe. As long as the original architect has the possibility to get it status back, its good. You could have the "abandoned" system new architect be either : the fastest player just like yet-to-be-colonized systems, or the system architect of the closest colonized system, or a player predefined by the previous architect, or have a bidding system (great money sink btw), or the player with the most activity in that system, or the one with the highest reputation amongst the factions (or the faction with the biggest influence) in that system, etc.