I've suggested maybe his injuries even came from someone else? Maybe not the bite but the fight type injuries...what if someone roughed him up like you idiot what have you done...or you idiot her phone is on, hence the drive back towards SOL?
All JMO/another angle
Tying together (1) his story to his co-workers, "I got these injuries in a fight" and (2) cell tower records/affidavit show he possibly returned to the area:
-Possible that CM did go voluntarily to EA's house (or, someone else's house in Allen that one or both of them knew).
-When they returned, someone was waiting there, and that person (the mysterious "other arrests could be coming" person?) fought with EA out of jealous rage of CM being with him...possibly hitting CM first, then attacking EA. All of this taking place at the rear of EA's car.
-Other person manages to subdue EA/wins the fight, takes CM, leaves. EA goes back home.
-Either then, or in the ensuing days, person (or, intermediary) tells EA not to tell police anything about that night or they will kill him, his family, or both.
-EA, recognizing problems, begins an earnest clean up effort with his car.
Far fetched. But, unfortunately, because of the type of people these people are said to have associated with - drug users and dealers - it's not any less plausible than any other scenario.
Wouldn't shock me if this is the angle defense takes if she doesn't return or isn't found.