The Testimonium Flavianum betrayes the same anti-docetist propaganda in the incipit:
About this time there lived Jesus, a wise man, if indeed one ought to call him a man. For he was one who performed surprising deeds and was a teacher of such people as accept the truth gladly
What need the Christian author had in pointing that Jesus was a "man"? This resembles the same enigma behind "born by woman, born under the law" of Galatians 4:4: all the Jews are born by woman and circumcised, and so?
The interpolator is aware of the paradox, and he explains it: the doubt about the humanity of Jesus is raised not by his being a Gnostic aeon descended on the earth "in form of men", but uniquely in virtue of his wonders done on the earth.
I wonder why those arguments have not been done before me, despite of the fact that the deniers of the total authenticity of the Testimonia Flaviana are thousands and thousands.