It's bare metal under the powdercoat isn't it? So if that flakes there's no protection at all?
Just because he's able doesn't mean it's a good idea, if it turns out to flake or not withstand stonechips or affect a painted finish you're in for a full bare shell rebuild again...
At the moment the shell is in etch primer to stop it rusting so it has got that underneath. As for flaking I think it unlikely but who knows.as for affecting the paint he powder coated my alloys an then 2k painted them the colour I wanted with no problems