Why isn’t Bernie Sanders making a bigger issue out of Hillary Clinton’s email setup, particularly in light of the news just before the Iowa caucuses that “top secret” information crossed Clinton’s home-brewed server?

That’s what Chris Cillizza asks today, and it’s a very good question. On Friday, in response to that news, Sanders put out a statement saying that “there is a legal process in place which should proceed and not be politicized.” On Sunday, on Meet the Press, Chuck Todd asked Sanders whether the email story gave him “any hesitation about her electability or about her honesty.” Sanders said:

“I think this is a serious issue. I am not going to attack Hillary Clinton. The American people will have to make that judgment. What I am going to continue to focus on is why the middle class continues to disappear and we have massive levels of income and wealth inequality and why we have a corrupt campaign finance system, which allows billionaires to buy elections.”

So why isn’t Sanders attacking her directly over it? Cillizza argues:

He is trying to stick to a pledge to run a different kind of campaign — not engaging in any sort of personal attacks — while making clear he thinks Clinton’s emails are a “serious” issue….That wink, wink, nudge, nudge approach might work for Sanders on Monday night while also preserving the moral high ground that he and his supporters quite clearly value. But, if Sanders winds up coming in just behind Clinton in Iowa….it will be hard not to look at his unwillingness to go hard (or even moderately hard) at Clinton on the email issue as a big reason why.

My reading of Sanders’s quote is that, when he said this was a “serious issue,” he was not saying that it is necessarily a serious problem for her, in terms of what it might say about her integrity or chances in the general election. What I think he meant (I could be wrong; it’s possible he was playing it cute here) is that the issue is serious enough to merit allowing the legal process to play out to determine what actually happened, and thus, he won’t use it to try to influence the primary. That’s consistent with his Friday statement.

Either way, as Cillizza notes, there may well be some second guessing about Sanders’s decision to hold his fire if he loses. It would be interesting if the reporting could nail down whether the Sanders campaign did internally consider going harder at her over this.

However, it’s quite possible that the Sanders campaign has a very good reason for not doing that, and it isn’t just that refraining preserves the moral high ground for Sanders. Perhaps more importantly, Sanders could not attack the emails without undermining the entire thrust of his campaign in a way that would go significantly beyond squandering his moral authority.

The Sanders candidacy is premised on the idea that our political system is failing people in a very profound and fundamental way — that it has been rendered paralyzed in the face of the immense challenges the country faces. For Sanders, the political media’s obsession with the Clinton email story simply represents another way in which our system is broken so irrevocably that it is incapable of addressing those challenges. This is plainly obvious if you go back to that hugely important moment during the first Dem debate, when Sanders absolved Clinton of the email mess, and watch Sanders’ whole monologue:

The roar of the crowd that ensued when Sanders said, “the American people are sick and tired of hearing about your damn emails,” was not just a roar of approval from rank and file Democrats enamored of Sanders’s gallant willingness to take the high road and give a fellow Dem a pass. It was also a roar of approval from voters who agreed with Sanders’s rousing, angry indictment of the larger point that the email story conveys about the political mess we’re in right now. Crucially, Sanders added that the email story really reflects the media’s much broader failure to focus on truly existential questions, such as whether we will prevent the middle class from “collapsing” and whether we are going to have “democracy or oligarchy” — and that produced even more sustained cheering and applause.

And so, for Sanders, the media’s handling of the email story (its obsession over the politics of it even as there is a legal process underway that is supposed to provide a real accounting later of what actually happened) represents another way the political system is dithering while the country teeters on the brink of allowing our democracy and middle class to slip away, perhaps irrevocably. This is why Sanders’s outburst became, for many Democrats, such a charged and meaningful moment.

Now, I don’t claim to know whether Sanders’s decision to refrain from attacking Clinton’s email setup is entirely rooted in a principled adherence to this broader story he’s trying to tell. For all I know, if Sanders doesn’t win Iowa, and if his candidacy looks like it’s in some trouble, perhaps he will begin going after her emails, to undermine her integrity and case for electability. But it’s hard to see how he could do this without diluting one of the ingredients most crucial to giving his candidacy the power it has gathered, particularly given that his own previous handling of the email story has transformed it into a massive symbol of everything he’s running against.