Right. I don’t know. You tell me what the mekor that she has to wear anything is.
It is hard to imagine it is a lifnei iver issue, since if so, there is much more of an issue with an attractive girl who is dressed properly, than a “less attractive” woman who is dressed in short sleeves.
In any event, holding posters of graphic pictures could only be lifnei iver, which is why I assume it it unrelated to this discussion.