Was it grandstanding or showing the millions of people who feel doomed that there's people within the government willing to fight what they consider an administration that's a threat?
We live in crazy times.
Little late to the party, I know, but it was grandstanding.
It'd be one thing if she privately conferred with the White House Counsel about a legal issue, and then resigned if they refused to listen. But that's not really what happened. The DoJ Office of Legal Counsel had already OKed it, and there was only one section that was a little thorny (restriction of legal permanent residents without due process). That section has since been resolved by clarification. Clumsily resolved, no doubt, but resolved.
What Yates did was deliver a speech stating that although the Office of Legal Counsel had OKed, it, she didn't feel the executive order was "wise" or "just." That's not what an attorney's role is. When I advise clients, I don't tell them whether I think the law is "wise" or not. I tell them what it is, and if they follow it great, and if not, well sh-t.. that's on them. You're not paying me to pontificate on grander notions of societal wisdom, you're paying me to advise you- can I legally do this, yes or no?
Now, let's peel this back a bit and look at what's really going on. Yates was a holdover from the Obama administration. She was out once Sessions got confirmed regardless, so she saw a shot and took it. She may or may not have political aspirations, but she wasn't about to pass over an opportunity to score some points with the left while she had the chance. And to be honest, can't really blame her. I'd probably do the same in her shoes, to be honest.