I don't think the bar is to prevent luggage slide, it is part of the recline mechanism - (?)

If you are tall then your feet are fairly long and if you upper foot rests on the bar, she might have been able to feel your toes on the underside of her seat - which could annoy. Either way it is a sensitive space , the forward passenger needs some " heel kick' space.

That said, she could have been more diplomatic, even if she were in the right. Harmony in the cabin is in everyone's interest.