The states is a free country. She can to work in a Scottish kilt or even a Halloween costume, it doesn’t matter. In the real world, it may not please your boss much and he might suggest that you dress differently (if there’s a specific dress code). Or he might even get dismiss you due to “other” reasons that “don’t” have to do with your attire.
But really, she can wear whatever she wants to work. People here wear shalwar kameez to grocery stores, parlors, malls, restaurants, what have you. Maybe she mixes it up. Western clothes some days and more desi clothes other days.
There are times that I’ll wear a kurta (if it’s not one that’s too long) over jeans or dress pants to work. It kind of looks like a tunic top. It’s no big deal.