No, it's not "poor instinct." It's a principled stand. Now that stand may hurt her, but it's consistent with who she is and always has been. It's the same reason she's calling for impeachment when it's not "strategically convenient."
Agree with it, disagree with it, whatever, but recognize it for what it is.
What I admire most about Warren is that she speaks Truth to Power and she doesn't take the easy road out of self-interest. She may not win as a result of her choices, and we'll get Joe Biden instead. But that's exactly the choice we're voting for: Someone who has the backbone to stand up for something and someone who gets along with everyone, including the credit corporations. Pick your poison.