Twitter's tribute to women rings hollow for some targets of abuse

"University of Maryland law professor Danielle Citron, who studies online harassment, said there's a disconnect between the outside perception of Twitter and harassment and what's happening internally. Citron has been working closely with Twitter's trust and safety team on issues of online harassment for more than two years.

"I'm not a cynic about [the ad]," she told CNN. "It's reflective of who the safety team is and I'm encouraged by it."

Citron said she's seen "some pretty seismic change" in how seriously the company is taking harassment issues compared to its early years."