I think it's pretty much impossible to understand the random prostitute table without the context of the fact that it is a subtable of a larger table of potential encounters in a city. And we might go further and say that the unstated assumption of that table is that you are in a bad part of town.
Harlot occupies one small portion of a 3 page description of the various encounters that are possible, which include many explicitly female and implicitly female options. It includes the possibility that the harlot is male, most explicitly a 'pimp'. The subtable and accompanying description are intended to make it difficult for the players to actually recognize harlots amongst the other possible outcomes, and for that matter, to distinguish recognize the other possibilities. From the varying descriptions, the harlots in question could be: assassins, beggars, clerics, demons, dopplegangers, druids, fighters, gentlewomen, goodwives, illusionists, magic-users, merchants, monks, night hags, nobles, paladins, rakes, rangers, thieves, wererats, weretigers, werewolves, or vampires. I think it's very notable that the harlot entry explicitly calls out that a harlot might be mistaken for a female magic-user or vica versa. It's like jumping up and down and saying, "Hey! DM. That 12th level Magic User could well be a woman!" They idea I think behind the table is to try to provoke a comedy of errors, where the PC mistakes some other sort of encounter for a prostitute or conversely mistakes a prostitute for something else. Gygax was quite fond of using the baser instincts of this players to get them into trouble. Accosting a noble, gentlewoman, goodwife, illusionist, magic-user, monk or beggar on the assumption that any woman encountered had to be a prostitute would definitely be big trouble. On the other hand propositioning an evil cleric looking for sacrifices, a vampire, a weretigter, a nighthag, demon, or doppleganger would lead to a different sort of trouble. Similarly, not every dandy on the street is a pimp.
And to a certain extent, prostitute is simply reasonable simulation of the assumed setting described in the 1e Player's Handbook - a frontier boomtown near ancient ruins and dungeons in a world that is drawn in part from medieval and certainly pre-modern sources.
I think what is most jarring to me about the appearance of the table is that I know as a matter of fact that this was a book being purchased by 6th-7th graders, some of whom were baby sitting their 3rd grade younger siblings. I think it's pretty clear that Gygax never imagined that was the audience for this book. Compared to that jarring contrast, any sexism involved in having such a table - if there is any - just seems really minor. I might feel different as a woman, but its hard for me to speculate, in part because I don't think all women who play D&D are going to have some sort of simple stereotypical response to this table either.
