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:http://www.letsrun.com/wp-content/uploads/2018/03/Screenshot-2018-03-01-at-16.57.39.png
But not this one:http://www.letsrun.com/wp-content/uploads/2018/03/Screenshot-2018-03-01-at-16.57.09.png
In the slow motion replay there was no contact though (regarding the first pic), it was Muir kind of moving outwards. But if you saw the replay, Muir wasn’t touched and didn’t get knocked out of stride.