Needless Style Mistakes

According to the AP Stylebook, how should the word  "protestor's" in the headline be spelled?

In the opening paragraph, which is difficult to read says this:

"Twitter Inc. has to turn over information about an Occupy Wall Street protetster's posts of face a fine, a judge ruled, giving the company three days to show it isn't in contempt of court."

Did the headline writer get it correct? Or did the writer of the story get it correct?

Associated Press publishes 'situational stylebook' for Sept. 11 anniversary

This September will mark the 10-year anniversary of the September 11 terror attacks. It’s an occasion that will be commemorated, both on the day itself and, in many cases, in the weeks leading up to it, with journalistic coverage of the events and their aftermath.
To assist its members as they create that coverage, the Associated Press just released a style and reference guide whose content is dedicated to 9/11.
The guide is intriguing — not only as a useful tool for the many journalists who will be, in some way or another, writing about 9/11 over the next few weeks, but also as a hint at what a Stylebook can be when it’s thought of not just as a book, but as a resource more broadly, says Megan Garber, writing for the Nieman Journalism Lab. AP’s guide (official name: “Sept. 11 Style and Reference Guide”) is a kind of situational stylebook, an ad hoc amalgam of information that will be useful for a particular set of stories, within a particular span of time.
Click here to learn more about the AP's Sept. 11 guide.