1) Stevens tripped, fell to the track and impeded the runner to the inside of her. She was DQ'd because either A) she impeded another runner, B) she was out of her lane, C) Ariana Washington went over and helped her up.
Even if you don't think A and C are justified, she definitely should be DQ'd for being out her lane, any runner should.
2) If it was a DQ then it should be fine if she runs another race. The argument that a DNF should take precedence over a DQ isn't logical in this case. Stevens got up and walked off with the assumption she had been DQ'd which isn't hard to believe as she was clearly out of her lane.
3) Georgia, as Coach Johnson said, did not file the protest in less than 15 minutes after the race. Georgia only filed it once they realized she was running. Maybe Georgia didn't realize it was a DQ and not a DNF (unlikely) or once they saw her go to the medical tent, they assumed she didn't get cleared to run.
4) There was a lot of impeding going on in the race. Honestly, Ellis should have arguably been DQ'd for going on the inside of Rogers on that first turn. It looked clean, but she actually made physical contact and pushed her out a bit.
5) The fact that 2 protest were filed and USC didn't file either of them was insane. I understand it doesn't hurt to scrap up $50 and put in a protest, but both of these were still cheap shots.