Quite simply, the IAAF has justified their ridiculous post-hoc decision on the claim that women running with men, pacers in front or to the side, represents an unfair aid, like a wind aided 100m race (from now on MA can stand for Men-Aided), and thus should not count as World Record. So is the problem the presence of men or pacers? As the issue seems to be that of "unfair aid" we must presume that it is the presence of pacers, in that they block the wind, worry about hitting the right marks, and allow the lead runners to relax a bit more through the early stages of the race. As most men in a marathon are slower than the elite women it makes little sense that the simple presence of men is in itself an aid. So, if the "unfair aid" comes from having pacers to run off of then Makau's world record should fall under the same guidelines and should NOT be a WR (as neither would Geb's former WR as he also used pacers).
If we divorce the issue from pacers and simply say that men and women in the same race allow the leading elite woman to run against the 2nd tier men and thus also have an advantage versus a women's only marathon where the lead woman would be all by her lonesome then we are in effect stating that "competing" is an unfair aid. Thus any WR, male or female, set when the two lead runners fight it out to the end should also not qualify as a WR. The logical conclusion of the IAAF ruling is that every elite runner should have to start in isolation 15 mins after each other. No pacers, no competing or team tactics, just every runner in isolation against the clock. So now I am being ridiculous but one absurdity begs for another.