I have No science or education to back this up, but well before I became involved with iodine, I felt that the white pus that was a result of these initial 'red acne bumps' were a result of white blood cells reacting to some kind of infection response. It was pure summation, but one that goes back years.
Yes you are 100% correct. I mentioned this in an earlier post since this can explain why the iodine does not always create what we normally think of as acne. If there is merely inflammation there will only be red bumps formed from the inflamed glands. If there is bacteria present that get trapped the white blood cells will attack the infection, and white blood cells will die leading to the pus formation.