Character is prostitute described as having "the mind of a 5 year old"

I recently read a book set in the 12th century, in England. One of the characters is a young woman who is a prostitute in an upscale whorehouse. She is repeatedly described as having “the mind of a 5 year old” and liking her job. The whorehouse is described as being a safe, well-run place.

Putting aside the difficulty of saying an adult has the mind of a 5 year old, whether it was possible for a whorehouse to be some bastion of safety, and the fact that this is a fictional character, what is your reaction to the idea of this character: an adult woman with an intellectual and/or development disorder who is working, apparently, happily as a prostitute? Does it matter that it is the 12th century, so her options would not be extensive?

12th Century England (hell, anywhere in the 12th Century) would not be hospitable for anyone with developmental disabilities. Give someone like that a roof over their head and food to eat and she’d probably think it was multiple steps up from being left to fend for herself.

Not to mention that a serious number of brothels in the time were owned by clergy … being in a brothel was a serious step up from being a streetwalker [or constantly raped homeless woman] there was actually fair amount of protection for those women who were hooked up with a brothel over even just a regular pimp.

Though medieval France [among other areas, but just because Tuchman dealt with France in Through A Distant Mirror] being married and dwelling with ones husband was not actually entirely safe either - medieval France very specifically had roving gangs of ssingle young men [think apprentices and journey men not allowed to be married by their guild masters] did the smash in the door rape gang thang. On the semi-plus side, as I seem to remember if you were a licensed prostitute you had a specific way to dress [again, as I seem to remember it was a matter of a specific color of trim, or something like that. I would have to dig out my copy of the book.] If you were assaulted, your pimp/bordello would reinforce their displeasure on the men involved as it was effectively theft from the pimp/bordello. And seeing that the owner of the brothel tended to be the high end ecclesiastic in the community, it could go fairly badly for the common guy involved.