As Twitter slashes staff and pares back moderation under Elon Musk, it may soon run into a problem it can’t ignore: its potential liability for copyright infringement. TorrentFreak reported last week that the company faces a lawsuit by celebrity photo agency Backgrid. Backgrid says that Twitter systematically failed to take down unauthorized copies of its pictures, arguing it shouldn’t be protected by American safe harbor laws for copyright. The allegations leave plenty of questions…