Perhaps Theophanes made the error in his one-line, and Baldhuri was more accurate in his substantially longer descriptions of the events?
Anyway, as with almost all your arguments - it seems to rely on a selective (in this case, a very selective) reading of historical accounts.
What is most telling though, is that Kennedy et al (modern day historians) don't give Theophanes' one line the importance you do. That speaks volumes.
Cheers,
Shafique