I've never looked at Ripley in that way. I think it stems from watching the movie from like 5 onwards, that the thought of her being attractive never crossed my mind.
I've always, from childhood and right through into my adult hood viewed that scene as her relaxing. After her ordeal, it was her getting comfortable. She'd been in those clothes, as far as I know, since they initally woke from hypersleep and given the stress she'd been in and exposure to things such as sweat, Ash's milky blood etc those clothes would have been fairly smelly.
If it was a male role, I would expect the same kind of behavior.