This is all coming from a guy who has only messed with Zig on a Windows box with a preference for tabs over spaces (except post indent alignment). Zig fmt works great, haven't had an issue, less difficult to get going than mingw or vs that's for sure.
Also none of what you put here is an an actual justification for stuff like this. This is like being in the twilight zone, why would anyone defend this?
Again Unix newline style is the least of the worries for whitespace, Windows and built-ins like Notepad handle it just fine for years now if that's what you code in. Try inserting tabs in place of spaces as you please in Python or Haskell though and yes you are likely to run into problems trying to run a program. It's not called "significant whitespace" in those languages because it's ignored.
It's fine to point out you think something is harder to use than it needs to be but the way you've done it says more about you than the language. You won't a whole language because it requires you run the built in formatter to compile? Might as well not use GCC either it forces you to use -- for options instead of / and other tools handle it just fine they just want to screw with Windows users that's it! What's left to talk about except these kind of nitpicks if that's where you draw the line for ignoring whole projects with years of effort put in them at?
None of what I put here was claimed as justification I said the Zig docs link to the reasons. Specifically (in case you'd rather I'd bring them up for you) the reasons were around ease of parsing as a large portion of the syntax was. The whole language specification is actualy very specific about making sure each line can be simply tokenized individually and parsed one way regardless of convetion - not actually so picked just to screw with people that like tabs or Windows. Zig fmt is allowed to "eat" any complexity in normalizing code (referencing ICU data, normalizing whitespace and other syntax, and so on) so zig build-exe doesn't have to. This philosophy of keeping as much functionality out of the core compiler and language is a big part of what allows Zig to target many places e.g. Rust doesn't even though Zig is still very fresh.
If running "zig-fmt" as part of your custom build process or using one of the editor plugins ziglang maintains that does this for you is "a slap in the face to users" I'm not sure there is any language those users would be happy with as there are other things they are going to like less than it replacing their whitespace on them. It's certainly not harder to do than post scathing reviews about how you couldn't just use tab on the release discussions though.