I'm guessing that you haven't actually seen California cars with basically ZERO rust. The time that it would take to get all the blasting material out of the car would more than exceed the time needed to use a metal etching chemical to convert the rust, scrub it off and then paint it so it doesn't happen again. I'm not suggesting that he should just POR15 it and forget about it, but with the proper prep its a perfectly viable option. If the rest of his car looks like the pictures he posted, blasting the car would do more HARM than good.
I would hit it with some phosphoric acid, you can usually just get it at a paint shop. Basically the same stuff that is sold as a metal etch prep for painting. That will convert the rust over to inert (it turns black). Then I'd use a 3M style scruffy pad to sand it off, you can get attachments for electric drills that will make that a snap. Then use a rust preventative paint like POR15 or Rust Bullet or whatever you prefer. If you do a good job cleaning it up some self etching primer would probably be more than sufficient to keep it from flashing again.