All I can see is with about 200m to go, she stepped out in front of the other Aussie (Hills) and made her move. She very slightly - maybe 1% - impeded her teammate, but it made no difference. Hills was spent and had nothing left.
If that is the reason, it's the softest DQ I've seen. That is just distance racing. I wonder if Gen knows she was DQ'ed, and protested it. Is there a time limit on protests for these meets?
What sort of official would be mean-spirited enough to DQ someone for that?