In one of two stories Thursday, Buzzfeed said its interviews of 10 former high-level Twitter employees found that the social media site had resisted harassment policies early on because it was built on free speech.
The article said Twitter's difficulty in "drawing the line" between free speech and harassment came amid pressures to raise revenue and compete for celebrities. The other Buzzfeed article alleged that then-CEO Costolo "secretly ordered employees to filter out abusive and hateful replies" to Obama, angering senior Twitter employees who supported unfettered free speech.
Though Costolo did not mention the Buzzfeed articles specifically, he tweeted that "sensationalist nonsense" of how trust and safety works at Twitter was "laughably false."
A Twitter representative told Reuters that the company was only contacted about the Buzzfeed story Wednesday night and had not seen any part of it until it was released Thursday.
"We are going to continue our work on making Twitter a safer place," Twitter told Reuters.
Buzzfeed declined to provide further comment.