I don't think it's overkill to explain a little more.  I do think that your proposed explanation might confuses matters a little more, just in the sense that "by treating the image as being at 0.2" resolution" is suggested as the reason why we don't need to apply a pixel convolution/deconvolution.  The point is more that the "SDSS PSF" images always include the pixel convolution already, so whether we want to say they are at 0.396" resolution or just lie to the code and say they're at higher resolution, the pixel response is already in there.  How about just "The SDSS PSF images already include the pixel response in them, which means that is no need for us to apply our own convolution with a galsim.Pixel."