Y Combinator CEO Garry Tan posted a rant on Twitter, saying seven San Francisco supervisors should 'die a slow death', which led to threatening letters being sent to their homes. Tan later apologized, but the incident has sparked concerns about the safety of public servants and the potential for violent rhetoric to incite harm. The supervisors who received the threatening letters have filed police reports and are calling for action to be taken against Tan. The incident has also raised questions about the use of the term 'moderate' to describe Tan's political views.