It doesn't matter if it tells anything about Jesus. It only matters if it is a reliable testimony to his existence which is the question at hand. You say it is not reliable and I am asking why. It is obvious that some of the one passage was made up, but I don't think there is any reason to think the whole passage was made up. I just can't imagine a Xtian scribe saying "hmmm, Josephus never mentions Jesus, so I think I'll go ahead and add a passage here so that future historians will have a non-xtian source for Jesus's existence." It seems more plausible to me that a scribe was copying
Josephus, got to the passage on Jesus and decided to alter it to reflect a Xtian message.
Yes, it is a testimony we are fairly certain has been altered.
It is really out of place, suggesting it was entirely made up, but even then.
We can't know it was there. We don't know it was not there. We can't know either way, hence, we can't
rely on it, either way.
I don't think it bodes well for the apologist that Xtian scribes were altering Josephus. An apologist might mention it when rattling off a list non-Xtian sources, but like you said, this source tells us nothing accept that Jesus existed and was killed. The apologist is going to be hard pressed to turn that into support for his faith.
Go to the thread (mis)named: "evidences for why we know that the new testament writers told the truth", over in the History sub section.
Anyway; yes, the whole quote is unreliable one way or the other, you can't bring it to the table of evidence one way or the other, as you can't trust what it says.
So, the only way one can use it is being lying about its level or reliability, lying is a common tactic of some apologetists...
Making a mistake seems more plausible considering the fact that, at the time, procurators were in control of Judea and the fact that the rest of the passage doesn't speak favorably of Xtians.
Maybe, maybe not, I am not an expert on the subject, to be honest.
How can that be certain? It could be the case that Tacitus just knew that the Xtians worshiped some guy that Pilot executed. There is no a priori reason for saying that Tacitus must have gotten that information from Xtians.
What?
Yes there is a very good reason... Nobody but the Christians remembered (or cared) about Jesus at the time.
There might have been reference to him buried deep into the reports Pilatus was sending Rome regularly (and I am not convinced the execution of one trouble maker would stand out enough to be considered worthy of mention) but there is no reason for Tacitus to go on and look for himself unless he was familiar with the story of Jesus.
He, pretty much, HAD to have learned about it from Christians and there is no reason to think he checked any deeper than that. Really, if Tacitus had cared about the subject enough to go out of his way to conduct independent research about it, one would have expected more than a throwaway line out of the 16 books of Tacitus' annals, especially considering the 5th book focussed on the Jewish rebellion...