In fairness, I don't have a habit of applying tight scrutiny to things that appear, on their face, to be blatant calls to violence. It's usually self-evident by reading the words.
Twitter's actions aren't even self-consistent here. If these tweets were all innocuous, then why remove the trend? If they were primarily discussions of other people's activity, rather than explicit calls for violence, then there was no good reason to do this.
Also, there's nothing "moving goal posts" about asking people to at least try to substantiate what they post. The person I responded to didn't even bother posting a link.