I don't think it should be a DQ. Under normal circumstances I could see the argument, but would generally say it's racing. However this had 2 different circumstances.
1) Dibaba drifted out into lane 2 to pass a lapped runner. Perhaps Hassan saw that and figured she had to get to 2 anway.
2) Should the fact Hassan's arms go so side all the time factor in? I think so.
This photo looks pretty bad:
But not this one: