Uh, no… the OP asked for honest opinions if the word he chose had an external significance that could distract from his overall text, and the consensus seems to be that it would. We’re anticipating problems, not jumping all over him.
Hell, he could call his planet something completely whacky like “Disneyworld” and he’d have the same problem. The issue isn’t political correctness, but that the term has a strong history of association with something totally unrelated to the story the OP wants to write. I’d recommend that unless the OP wants to invoke some kind of Israeli and/or religious imagery, he’d be better off choosing an arbitrary name without the historical baggage, which happens to include a racist book as well as several recent sci-fi action movies.
Calling your government “Zion” is right up there with deciding to call a twisty little city with a river through the middle ‘LONDON’ because you like the sound of it, or naming the leader of a fictitious government ‘Adolf’ (regardless of his last name). The reactions you get will range from “Hey, that was the name of the city in The Matrix” to “He’s a horrible anti-Semitic piece of wasted flesh,” and everything in between.
Let me put it another way: imagine you’ve got this Mexican character who gets framed for a crime he didn’t commit, and the local government succumbs to mob rule, and nails him to a tree. You cannot name this guy Jesus, I don’t care how you pronounce it in your head.
(And a helpful aside: if you write a character whose initials are “J.C.”, literary critics will assume he’s meant to be a Christ figure. Now you know!)
Zion would probably be bad, but Zebulon just sucks. Between the two I’d go with offensive over banal. Certainly you can pick a better one.
If the whole thing is about homeland, you could pick maybe “Bethel” - I think “Beth” means home (or am I totally misremembering?) but plain old Beth is no good.
And, yes, the same kind of link could be made, and somebody could choose to be offended, but it’s less overt.
“Bethel” is a bastardization of Beit El - House of God. It’s a pretty good name.
Let’s see, other biblical names…
There’s Shiloh, the Israelites’ holy city before the temple. It’s sounds almost America, too.
There’s also Goshen, the land in the Nile delta where Jacob led his people. A bountiful land, but if you stick around too long they’ll make you a slave and kill your children. Pretty evocative.
As Zion originally was the name of a mountain in Jerusalem, how about another hilltop - Moriah? It’s the one where the Temple originally stood. The name be a bit Tolkienesque, so don’t forget that extra “h”.
I’ll tray and think of more, but I think the ones I’ve given so far are already better than “Zebulun”.
Reading through all of the suggestions so far, I think you’d do well to name it “Promise” I do believe that Zion is going to get you in trouble on nearly every front you’ve seen here from Zionism to Protocols to Matrix.
“Promise” on the other hand has great promise given your hinted at deeper meaning and all.