You don't need to know anything about the political alignment of anybody to know that a person wishing a politician would die is legal political speech in America, and not even an uncommon sort of it. This sort of thing is regularly said by Americans of all political persuasions about politicians in any and every political party. The article is making a mountain out of a molehill.
For my part, I hope Trump dies painfully, as well as every other living American president (with the sole exception of Jimmy Carter who was a terrible president but a good man nevertheless.) If you live in America, I know you frequently hear people saying they wish X Y or Z politician would die. Such harsh sentiments are commonly expressed in American society. It's a free country and lots of people exercise that freedom with inflammatory but legal hot takes like that.
I think everyone agrees that Tan's speech is protected by the First Amendment. As is strong criticism of his speech. No one is proposing Tan should be fined or thrown in jail or have his rights curtailed by the government.
It is not normal and should not be normal for major political donors to make public death threats to local officials in the city where they live, even as a joke. It's toxic and corrosive to society and politics, and makes him seem unhinged. Tan is rightly getting excoriated, and he deserves scorn from his own political allies for significantly damaging their common causes.
Tan keeps complaining about SF politics being frustrating, but in my opinion, as someone who supports a significant portion of his policy platform, local politics would be improved if Tan would just move somewhere else or shut up and keep his money to himself and leave political discussions to the grown ups.
For my part, I hope Trump dies painfully, as well as every other living American president (with the sole exception of Jimmy Carter who was a terrible president but a good man nevertheless.) If you live in America, I know you frequently hear people saying they wish X Y or Z politician would die. Such harsh sentiments are commonly expressed in American society. It's a free country and lots of people exercise that freedom with inflammatory but legal hot takes like that.