It is not that easy merging into a race and while Mu merged a bit quick, she could not see what was behind her. They could have called the race back but I do not even know if they would do that for one runner going down. Akins was the one who could see where most people were . I don't necessarily think women merge incorrectly or whatever the poster said comparing women and men. But generally, it seems like women like to run in a pack and sometimes close enough to have collisions.
However, high stress, nerves can lead to people making mistakes in racing. You are supposed to clear people (i.e. have enough distance away from them) before you cut in, otherwise there would be bodies flying all over. I wouldn't call a DQ. I would hope it does not happen again. I would have to look at the rule book to say anything definitively and study the tape. I find it difficult to believe she does not know how to gradually cut in given how many 800's she's run. Maybe chalk it up to nerves.