This is the alleged harassment: he invited her to Trump's dinner (she believes all Trump supporters are racist and support white supremacy), and then made a profile picture mocking them being in love: https://www.theguardian.com/us-news/2017/jan/09/martin-shkre...

Edit-response to comment below due to rate limit: indeed "if I'm acquitted, I get to fuck Lauren Duca" is quite rude, but mocking journalists isn't harassment and more to the point: it was after Duca claimed Skreli was harassing her. Don't misrepresent.