It’s possible that:
1. Fedex assumed SWA aborted and that’s why Fedex flew straight ahead over the runway.
2. Tower assumed SWA aborted and that’s why they gave them a right turn instruction, typically a runway turn off call.
3. SWA assumed Fedex went around and that Fedex knew SWA took off and that Fedex had made a sidestep maneuver for lateral separation.
No one should have had to make these assumptions. There was unclear and non standard phraseology from all parties involved which led to confusion and a lack of clear control of the situation.