Not crazy, quite doable.

That is a 'premium' service with special rules and perks. I think depending on how far your niece is from DCA and where in Manhattan (assuming that, Queens might be even better) she is going, she might beat her current commute time. Since she's commuting daily, she won't be checking bags, unless she has to carry verboten items, so her time to check in is only 15 minutes before departure and she has to be at the gate only five minutes before.

However, it might be easier on her to negotiate perhaps staying in NY Monday to Thursday and working from home on Friday. That's infinitely easier, but then she needs to find a place to stay. Her company would save the daily $350 in commuting costs, and divert that to hotel instead. Planning ahead, that price isn't nuts.