None of your criticisms make sense to me, this is some of the best local journalism I've seen in a while. The headline is a tl;dr of the entire piece and the first several paragraphs are the facts directly related to the incident and providing essential context. Nothing is sensationalized, there's no sob angle, and they even corrected a minor inaccuracy. The way you describe it is like it's a tabloid covering some nothingburger, but this is a clean summary of an important event: people are threatening SF supervisors, and it's a result of a drunken Twitter rant by Gary Tan. This is what is happening, and this is what the article describes in clear and direct language.
What else could you even want from this article? That they just elide the liquor angle? That they don't cover it at all or spend the entire article analyzing the person who sent the threats? A person in power wished death on a political figure, and people acted on that wish. This is absolutely news worthy of an article in a local blog, whose beat overlaps with the political jurisdiction of the threatened politicians.