I read it over a few times and see that it is not the paint he was worried about removing, but that the metal still would have residue of the paint remover left in the pores of the metal. I suspect he worried that new paint would not go on right with any of the paint remover not gone completely. I would think instructions on cleaning off the paint remover would be indicated on the painter remover instructions.
Sand blasting if you can do that would be best. I could not get the whole frame in the shops mid size sand blaster. Also some powder coated paint on the engine just does not come off easily with either careful sanding or various goop type paint remover.