Even the history of zionism is more complex, and it has been captured by the worst demons of the ideology.

Sure, it's inherently problematic for anyone who values the separation of state and religion, and in a modern political landscape it does read like a recipe for disaster. Based on the old testament and Jewish history however, it's easy to see the romantic appeal of Zion without it at all justifying the terrors of modern zionism.

So I agree with your point completely - I just wouldn't treat Zion as a slur. That said I also don't think zionism in its contemporary form has any legitimate role to play, and it's a cancer on the world like so many isms before it.