Why doesn't Kana's boss know about the Day of Flight?

Question

I'm currently rewatching Haibane Renmei. In episode 4, we see this exchange:

Kana's employer: Hey, is Kana going away?

Rakka: Oh, not at all. I didn't come to replace her. I'm just visiting everyone's workplace because I'm new. Kana loves it here. I can tell.

Employer: I see. Well, with those wings of yours, they make me think she might just fly away on me one day.

Rakka: They look fancy, but they don't actually work at all.

Employer: I see. That's good, then.

It's quite clear from this exchange that Rakka does not know about the Day of Flight, which is probably to be expected, as she's a newcomer who does not learn about it until Kuu leaves.

However, what struck me as strange was that Kana's employer (who looks relatively older and who isn't a Haibane) seems to have no knowledge of it (as might be inferred from his question). It would appear that he is old enough to possibly have seen other Haibane disappear in the past. There are two obvious ways to explain this for me. However, I'm not sure if either of them is correct:

1. Beyond the trading that the Communicator does with the Toga, the normal townspeople don't have many personal interactions with the Haibane, so they wouldn't notice if one disappeared one day. The townspeople might have a basic understanding of how Haibane life works (so wouldn't be surprised to see the teenage Rakka appear as a "newborn" one day) particularly if they often interact with them, but they wouldn't be aware of the specifics.

   However, given the limited number of places where Haibane can work (in episode 3), I'm not sure how true this is, since the people who work there would probably be slightly more familiar with things, even if the townspeople seem to outnumber the Haibane.

2. The Haibane are seen as somewhat separate: the employer earlier tells Kana:

   The clock tower in your home. Go repair that yourself. [...] We're not supposed to meddle too much in the Haibane's lives.

   This might mean that the townspeople might not delve into the specifics of the Haibane's lives, and that the Haibane are responsible for themselves. However, this is more of a general statement than anything, as we see in episode 3 that the housemother isn't a Haibane. Moreover, this would only mean that the townspeople might not bother inquiring after the Haibane who have disappeared (even if they might not know why they've disappeared): it does not mean that they do not necessarily know that the Haibane -- or at least the Haibane outside of the Federation -- eventually "go away".

Is there a more satisfying explanation for Kana's employer's ignorance about the fact that the Haibane eventually "go away" than these? Or do I already have the best explanation we can get? (Again, I wouldn't expect him to know the exact specifics about the Day of Flight beyond that the Haibane eventually leave.) Alternatively, am I possibly just misinterpreting the exchange? (I could see the first line as implying that the boss does indeed have the Day of Flight in mind, but what he says afterwards seems slightly out of line with that.)

Answer 1

In episode 7, Reki states that she was despondent after Kuramori's disappearance. Nemu tried to cheer her up by doing research at the library to find an explanation for the disappearance. This explanation ends up being the "legend" about the Day of Flight at the library. Thus, information about the day of flight must be openly accessible.

In the same episode, Rakka tells the cafe owner that "Kuu has left us." In response, the cafe owner asks if Kuu has disappeared. After that is confirmed, he says, "But that's how you Haibane are, right?" Thus, Kana's employer is not an anomaly if he knows about the Day of Flight and other details about Haibane life. With the rest of the content in the exchange with Rakka then, it looks like Torisuda's suggestion (that the employer is aware of the Day of Flight on some level and simply didn't want to explain in detail) is relevant here. (After all, the details in his exchange seem too accurate for mere speculation.) It's still possible that he doesn't actually know, but what I'm trying to assert is that the scenario where he does isn't improbable at all.

However, it's worth noting that not all of the townspeople are familiar with Haibane life. In ep. 5, Sumika tells the presumably teenaged Rakka that she does not look like a newborn, despite being good friends with Nemu. Similarly, in ep. 8, a woman in the thrift store treats Rakka in a somewhat objectifying way, which might be grounds for assuming a lack of familiarity with the Haibane.

Thus, it must be then that the Haibane are "separate" enough that a number of people get by without ever having any meaningful interactions with them, while a small number do (and thus might be more familiar with Haibane life).