There is no more succinct way to describe a Zionist than by using the word Zionist. To assume anyone who says "Zionist" means "Jew" is to make an unnecessary leap in bad faith.

Racist? Yes.

A threat? No.

“Fuck Jews” cannot reasonably be interpreted as a threat.

It’s a nasty antisemitic thing to say, but that’s all it is.

Eh, most Nazis that use the words interchangeably really do use them interchangeably. Like, they'll talk about the Jews controlling everything in one sentence and say it's Zionists pushing cultural Marxism or whatever the next.

You realize that calling everyone who criticizes an ongoing genocide an antisemite isn't workable, right?