Mix bleach and vinegar and you still get the toxic gas. It's the bleach that is dangerous here rather than the weak acid you mix with it and makes it off-gas clorine. Just about any acid will cause the clorine to be chemically released from the bleach.

Vinegar and OA are very similar if you are using them well diluted with water. Both are dangerous if you use them too strong as the MSDS for acetic acid will show you. it can be bad stuff if it is too strong and OA is no different.

The chemical properties of OA caused it to really love rust and attacks it while vinegar does a fairly poor job unless it is very much stronger and even then it misses a lot and you need to scrub by hand. Rust is funny stuff and holds moisture. If you miss even a LITTLE bit it will start again because of this -even f you seal it over completely. Rust is like cancer and it'll continue to grow unless it is killed dead dead dead and OA has the exact properties to really kill rust where vinegar only chips at the surface. It looks OK from the outside but it's still down there under the pitting waiting to grow again like a seed.

OA is sold as wood bleach. It's used by deck cleaners and sprayed all over the place in concentrations tens if not hundreds of times stronger than anything needed to use on bicycles. We've got TIME on our hands and over 12-24-even 48 hours it can do the work. If people think it is too scary to use then fine. But like just about everything in this world it can be abused or used incorrectly.

I'd like to see someone with the correct credentials talk about the fear of kidney damage/stones using OA. If it were this bad I'm sure that all the deck-cleaning products (and cleaners like barkeepers friend) wouldn't have any of it in there.