This is the best angle and resolution I've seen (mute it first):
This is the closest I've seen to evidence for a double touch but even at that, I don't think you can definitively say it's his standing/slipping foot that hits it and not the turf between that foot and the ball.
Exactly this, heard people say this puts the argument to bed, but it doesn't at all. As you say the ball could move slightly because of the turf shifting.
Also if both feet are hitting at the same time then wouldn't that be allowed as it is with free kicks? The laws only state you can't touch it again AFTER your first touch, not that you can't kick it with both feet at the exact same time.