I wanted Muir to get past more than most of the Americans here, but I don't think Hassan did anything wrong.
She always runs with her elbows out, people that have seen her run knows she does that even when running solo out in front. It's just her arm swing.
And as for the gliding out of lane 1 into lane 2, I personally don't think that's illegal and if it is it definitely shouldn't be.
The runner in front has worked hard to gain an advantage position, it's madness to say they have to run in a dead straight line for the finish and must no deviate. Does everyone realise that running at a diagonal also increases the distance the athlete in front is running? So if they are tying up it's a risk to run further.
I personally think it's a completely fine tactical move no worse than a bit of barging in the middle of the race.
If you've decided to leave your kick until the last 50m of the race to pass me after using me as a windshield/pacemaker for 1450m then you better prepare to run in lane 6