New Minion positions are generally opened when former ones 'retire' or the section grows to a point where it becomes necessary to bring on more help. As far as non-section active minions go, this seems to be common with sections that aren't as popular or games that through time or circumstance become somewhat niche. In many sections it seems that there are quite literally no regular contributors that would apply/be qualified to moderate the section, and in their place come sort of "power-minions" that moderate a great many sections, both active and inactive.
You could definitely talk to Dave, Arun, or any GM or SA and up, but I would assume they have somewhat of a standardized metric for when it's necessary for bringing in new minions; meaning that with the sheer state of inactivity in the CA community it probably wouldn't be deemed necessary. If the discussion is there I could definitely vouch for how instrumental you were to this section in the early days.