I myself am a woman and pursuing my graduate studies in this field. There's no gender bias here in calling out flaws in work that's deeply technical. I have given similar reviews to some enormous claims put forward by my peers(men and women). I agree that person2 could have been more subtle on a public forum. But not even for a second did I associate a gender dimension until person1 brought it into the context.
Since we are talking history - with some search - I found out that Person1 has recently put out a #metoo experience and called out some incidents at Caltech. Don't you think there's not even a little bias here against every possible "person2" who happened to be a male and just gave a technical feedback? Not like that's an invalid statement. He does have valid points in what he said(just the way he said it might not have been ideal). But it escalated very quickly!