If anyone writing about Ms. Reade has discussed what everyone is told about what not to say about past employers, I have yet to read that discussion.
I have never really understood why you're supposedly not supposed to say anything negative about a past employer. I am still not convinced that you have to say only positive things about your last job to be hired for another one. However, if most people think that it's wrong to speak ill of a past employer, because that's what most people have been told, then they will think you're doing something wrong if you speak ill of a past employer.
Isn't Ms. Reade now saying something negative about a past employer? How does everyone feel that's working out for her?