Seriously? I believe you're making it difficult. I think what makes it appear to you that "this such a difficult concept" for others is that your detailed facts are outside of the context of the op. The unexpected lacking relevancy creates confusion.
The op begins with the misnomer "active bass" and essentially poses the question "Are passive pickups necessary for a passive option?" I think only the op knows precisely what was meant by the question. I have my interpretation and you have yours, but absolute fact of it isn't certain.
I believe that the op had a fundamental misunderstanding that his bass with active electronics was an "active bass," and he believed this meant it had active pickups. I believe his confusion was at knowing of other "active basses" with active/passive switching, yet being told that passive pickups were "the only way to have a passive option."
He was correctly told that in order to have switching between active and passive operation, you have to have passive pickups. It was further explained that most commonly, basses have passive pickups and active electronics and that's what his bass has.
Case solved IMO.
You apparently felt it necessary to add that one does not necessarily have to have passive pickups to install a preamp with a active/passive switch. While technically true, I'm not sure exactly how relevant or helpful that information is in the original context of the thread, but put just the right way, it's enough to inject some confusion.
Further, your words are blending and blurring a core distinction when you address the active pickup as though its "activeness" involves something that exists apart from a preamp. An active pickup is made "active" by power supplied to its preamp.
When you make statements like "Active pickups are always active, preamps can be put in, or taken out of the circuit," that suggests that you are saying active pickups are active independent of a preamp and that causes confusion as to your meaning.
