Right, they are under no legal obligation to respond to a Tweet.If she wants to subpoena Disney to come testify... sure. Otherwise Disney can tell her to pound sand.
The issue here is one of regulation, of which her opinion has merit. That's not offering my opinion of her opinion, but her position to create and vote on laws is absolutely relevant.
Full disclosure, I have my reasons for not being a fan of Elizabeth Warren and I voted democratically across the board this election (she was not up for re-election in Massachusetts).