Well, if the bumper is straight, then your only option is to grind off the paint and replace or reshape that area of the quarter. Maybe there is just some filler there. Hard to really tell until you get in there and poke around. As long as your guy can blend well, you shouldn't have to repaint the whole quarter. A good painter will save some left over paint just incase there needs to be a touch up. The painter I know has a wall of small paint cans labeled with what car they go to. Keeps them around for a year or so, then recycles them. Tinting can be a nightmare for the inexperienced and the wrong tint on a touchup can really stand out. On a driver car, I would trim the bumper and touch up the edge with some silver paint, or shim the bumper out to clear. Kinda hacky, but works on a cheaper build. It's really up to you what you want to cut or bend to make the bumper and quarter play nice. I just hate to cut into fresh paint. It's a tough spot, but can be fixed.
base coat over the work he did to "semi" match the rest of the car... He figured I'd appreciate that more than the primered look ... Still have doors, fenders and hood to do, then the real paint job comes.