Facebook abruptly removed ads for pot legalization group Just Say Now, saying the ads' marijuana leaves might encourage Facebook members to try toking. A social network founded on college campuses can't really think its users are strangers to pot.

It seems a lot more likely this ban is about money, and appealing to top shelf advertisers.

Facebook is trying to imply the pot ad ban is all about protecting users' health. "The image of a pot leaf is classified with all smoking products and therefore is not acceptable under our policies," a Facebook rep told Just Say Now, according to the Huffington Post's Ryan Grim.

Just Say Now started a petition calling the ban an "unacceptable" impediment to political speech. The Libertarian Party is also unhappy after ads featuring its own leafy logo were vetoed by Facebook.

It makes sense that the groups are taken aback. After all, Facebook claimed to be on the cutting edge of "social norms" when trying to justify its own rollback of consumer privacy. CEO Mark Zuckerberg went so far as to say in January that it's Facebook's job to follow hot on the heels of social change:

"We view it as our role in the system to constantly be innovating and be updating what our system is to reflect what the current social norms are."

And yet when it comes to pot leaves, Facebook is about 50 years behind society, judging from its ad restrictions. Which probably has something to do with trying to keep Facebook attractive to big spending, blue chip ad clients who don't like their campaigns surrounded by seedy looking pro narcotics narcotics ads. It is, of course, Facebook's right to make that call, and probably a smart thing to do from a business standpoint. But it does put to lie the company's high-minded excuses about its privacy rollbacks and how they were "not about the money." (When people say that, it means it's totally about the money.)

[Top: Photo illustration of Zuckerberg holding a joint]