I've never heard of this method:
But baking soda is a mild abrasive. but, using water on blasted metal, which it would be in effect when finished. Is like playing Russian Roulette!
I'd use a flake off type stripper, one that goes on wet, then you wait till it dries, and everything comes off in flakes. It's also environmentally friendly, because you only have solid waste to deal with when dried.
Rust usually hides in the window checks, so stripping a car without removing the windows, is a half assed job, at best. If you aren't going to remove the windows, don't bother stripping it!
Also, consider taking off the window whiskers on the door and quarter windows, they are a good place for rust to hide.
I hope this helps?
Refinish King