Doesn't sound right to me... I would think you should be able to use a sealer over the old primer... I've never dealt with this, I usually take 'em down to bare metal. I disagree with the thought that enamel covers better than basecoat/clearcoat. A finish is only as good as what you put it on. Maybe he's not experienced and color sands and polishes the final enamel finish to rid it of the flaws... How much bondo did he use? Maybe he needs to invest in a hammer and dolly... Just my $.02 worth.
