Dealership experience means nothing. He could have been doing oil changes and tires the whole time or just maintenance items and worked on all newer cars with no real problems to figure out.
I wonder who this shop is.
To be fair vibration problems on older cars are hard to pinpoint. He just went about it in the wrong way. But the explanations he gave would tell me he doesn't know what he is doing or he is trying to BS you.
My recommendation is to stick to forum sponsors as they have experience fixing actual problems and not just 'dealership experience'.
There is a forum sponsor in the east end. Stance Factory. Check them out if you are looking for something closer to you.