Rep. Marsha Blackburn (R-Tenn.). (Andrew Harrer/Bloomberg News)

Marsha Blackburn owes Twitter one big thank-you.

By rejecting an ad for the Tennessee congresswoman’s fledgling Senate campaign that mentioned Planned Parenthood selling “baby body parts,” the platform provided Blackburn an early publicity boost.

“@Twitter continues campaign against @GOP,” former White House press secretary Sean Spicer tweeted.

“Here’s the Marsha Blackburn video Twitter banned. It would be a shame if this went viral & helped her win!” winked the alt-right activist known as Baked Alaska.

“The conservative revolution won’t be stopped by @Twitter and the liberal elite. Donate to my Senate campaign today!” the Blackburn campaign account implored.

Twitter did not, as some coverage has suggested, “ban” Blackburn’s ad entirely. It simply refused to sell her space for promotion. That means Blackburn’s ad is still viewable to anyone who searches for it, and the controversy Twitter has provoked means plenty of people will. The best part for Blackburn? She won’t have to pay a penny.

The worst part for the rest of us: This firestorm may have been avoidable.

Twitter turned down Blackburn’s ad because the platform deemed her “baby body parts” comment in violation of its policy prohibiting “inflammatory or provocative content which is likely to evoke a strong negative reaction.” Well, yes. Inflammatory content likely to evoke a strong negative reaction is the bread and butter of campaign ads. By assuming a regulatory role, Twitter has set itself up to get knocked down: It’s hard to play arbiter without starting to look arbitrary.

But Twitter has another advertising prohibition that isn’t arbitrary at all. Ads cannot contain “misleading or deceptive claims.” And that’s the more important point about Blackburn’s assertion that she “stopped the sale of baby body parts” by Planned Parenthood. It doesn’t matter how offensive it is or isn’t. Either way, it is false. Twitter should have banned Blackburn’s ad for that reason, and not touched the “inflammatory” question at all.

Blackburn is referring to the 2015 pseudo-scandal in which an antiabortion group released aggressively edited footage of a staged conversation with a Planned Parenthood representative to “prove” that the nonprofit made money off the fetal tissue from late-term abortions. A judge in Texas last spring concluded there was not “even a scintilla of evidence” for this claim. Other state investigations found no wrongdoing. Neither did congressional committees convened to take the organization down — Blackburn’s included. (Some Planned Parenthood clinics did, pursuant to the law, allow patients to donate tissue, and they accepted payment to cover the costs of the donation.)

As a popular weapon in today’s culture wars, Twitter is in a tricky spot when it comes to controlling who and what is permitted on its platform. Its leaders have seen that already. When they don’t kick off white supremacists, they’re accused of sheltering racists. When they do, they’re stifling the free speech that made it such a success in the first place. Yet with the Blackburn ad, they waded into the same waters where they knew they would flounder.

If Twitter’s executives take this debacle as a lesson, though, maybe they won’t make the same mistake again. Their platform is mired in the free speech debate, but it’s also on the frontlines of the fake news fiasco. Conspiracy theories, domestic and imported, swirl around its servers. Both problems require careful consideration, and perhaps clearer policy. But when the two intersect, as they did last weekend, Twitter shouldn’t waste its time quibbling over how inflammatory is too inflammatory. Twitter has vowed to fight against falsehoods, and Blackburn’s would have been a good place to start.