Most people don't choose low paying physically demanding jobs when they can paste together stack overflow answers.
That said, "Evil Maid" fits here because of that - they are no someone that you expect to need technical protections from but theoretically they could be a genious adversary or just hired by one.
I tend to agree with your analysis. But that is precisely my beef with the term. You seem to be saying that the term fits _because_ it describes a population that violates security expectation, _because_ it is "generally not smart, except for theoretical surprises" or "easy to hire for nefarious purpose". Neither one is very flattering, neither one equates to "evil" and neither one applies specifically to maids. A neutral term would have been an "adversary with temporary physical access" but that is not nearly as catchy.
That said, "Evil Maid" fits here because of that - they are no someone that you expect to need technical protections from but theoretically they could be a genious adversary or just hired by one.