Right, Josephus was a Jewish sellout, mind you he had little to no choice at that, working for the Romans, rewriting history of the Jews and everything else to please the imperial Roman victors.
"Moreover, the evidence points to the appropriate biblical term as “Chrestians,” not “Christians.” In this regard, if we look at the Codex Sinaiticus (Acts 11:26), one of the earliest extant manuscripts of the Bible, dating to the fourth century, we can see that the original word is “Chrestians,” with the “e” or eta (Η) erased and replaced by an “i” or iota (Ι)."
The above article constitutes an in-depth analysis that leaves little wiggle room for the Josephus apologists.
For the background, in my other Josephus article appears this list of arguments against authenticity:
1. It was not quoted or referred to by any Christian apologists prior to Eusebius, c. 316 AD.
2. Nowhere else in his voluminous works does Josephus use the word "Christ," except in the passage which refers to James "the brother of Jesus who was called Christ" ("Antiquities of the Jews," Book 20, Chapter 9, Paragraph 1), which is also considered to be a forgery.
3. Since Josephus was not a Christian but an orthodox Jew, it is impossible that he should have believed or written that Jesus was the Christ or used the words "if it be lawful to call him a man," which imply the Christian belief in Jesus' divinity.
4. The extraordinary character of the things related in the passage--of a man who is apparently more than a man, and who rose from the grave after being dead for three days--demanded a more extensive treatment by Josephus, which would undoubtedly have been forthcoming if he had been its author.
5. The passage interrupts the narrative, which would flow more naturally if the passage were left out entirely.
6. It is not quoted by Chrysostom (c. 354-407 AD) even though he often refers to Josephus in his voluminous writings.
7. It is not quoted by Photius, Patriarch of Constantinople (c. 858-886 ad) even though he wrote three articles concerning Josephus, which strongly implies that his copy of Josephus' "Antiquities" did not contain the passage.
8. Neither Justin Martyr (110-165 AD), nor Clement of Alexandria (153-217 AD), nor Origen (c.185-254 AD), who all made extensive reference to ancient authors in their defence of Christianity, has mentioned this supposed testimony of Josephus.
9. Origen, in his treatise "Against Celsus," Book 1, Chapter 47, states categorically that Josephus did NOT believe that Jesus was the Christ.
10. This is the only reference to the Christians in the works of Josephus. If it were genuine, we would have expected him to have given us a fuller account of them somewhere."