Where my Alero hasn't showed any rust in that spot, I'm sure it's there. You have to ask yourself if it's worth fixing. Any shop that is going to flat out say "It's going to cost more than it's worth" is really saying one of 2 things.
- We don't feel like fixing it
- We don't feel confindant enough to fix it
Being that he said "It will come back" I'm leaning towards number 2.
Ask fellow car guys in work. Do you go to church, supermarket, The Y, etc where they might have a paper or a corkboard with flyers and so on?
Shop around, you don't have to take the first offer.
I took my Delta to only 2 shops before I picked one. The first shop told me they would sand and paint, the second shop sent the car to a soda blasting shop first, taking the car down to bare metal, then bodywork and paint for only a $500 more.