Each pixel is defined by 32 bits -- 8 R, 8 B, 8 G, 8 A. Even if alpha is 0, there has to be information stored in Red, Green, Blue. There can't be "no information", because then a pixel is not defined by 32 bits of information. There is always a "color" (RGB values) for transparent pixels. Some editors will set the RGB values to 0 or 255 when fully-transparent pixels are saved/output. Others don't.
As the author mentions, certain resampling algorithms might be naive or plain ignorant about how to resample images with potentially transparent pixels. Should transparent pixels not count to the final pixel? Should all pixels be averaged? Should the output pixel be the median or mode value? If the image is being resampled to 1/3 its size the resampling can be very cheap if only the middle of the 3x3 pixel cluster is selected as the output value.
As the author mentions, certain resampling algorithms might be naive or plain ignorant about how to resample images with potentially transparent pixels. Should transparent pixels not count to the final pixel? Should all pixels be averaged? Should the output pixel be the median or mode value? If the image is being resampled to 1/3 its size the resampling can be very cheap if only the middle of the 3x3 pixel cluster is selected as the output value.