ISP earlier you quoted Doughty on Tacitus:
Doughty said: But the real question concerns the historical reliability of this information -- i.e., whether we have to do here with a later Christian insertion. When I consider a question such as this, the first question to ask is whether it conceivable or perhaps even probable that later Christians might have modified ancient historical sources; and the answer to this question certainly must be yes! Then, with regard to this particular source, I note that the earliest manuscript we have for the Annales dates from the 11th century, and must therefore have been copied and recopied many times, by generations of Christian scribes (and Christian apologists). So there were certainly opporunities to modify what Tacitus originally wrote.
The following is a response to the specualtion that it is an interpolation (also keep in mind that there are at least 7other early references to Pilate crucifying Jesus).
http://www.tektonics.org/tekton_01_01_01_TC.html
Is this a genuine reference, or are there doubts about its veracity?
Very few would assert that this passage is a forgery [though see Cutn.JGMM, 111-2], for the evidence is strongly in favor of the genuineness of this passage. The passage is in perfect Tacitean style; it appears in every known copy of the Annals (although there are very few copies of it, and none dates earlier than the 11th century), and the anti-Christian tone is so strong that it is extremely unlikely that a Christian could have written it. (Indeed, the Tacitean polemic against Christianity is so strong that it was one of two things Tacitus was condemned for in the sixteenth century - the other being that he wrote in bad Latin! - [Dor.Tac, 149] , and it is even said that Spinoza liked Tacitus because of his anti-Jewish and anti-Christian bias! [Momig.CFou, 126] )
This is not to say that there are not those whom we may encounter who will suggest that this passage is an interpolation. Some will weakly suggest that because no church father quotes the passage early in church history, it must have been added later. No church father, however, would have willingly quoted such a negative reference to Jesus and the Christians; moreover, indications are that Tacitus wrote for a very limited audience of his peers. The Annals may not have gotten into the Church's hands at an early date. The idea that this passage is an interpolation is no more credible than the idea held in the 19th century that Tacitus' entire works are fifteenth-century forgeries!