Was he a witness? When did he write, when did it happen?
If they are too far away, he can’t be a witness.
If he was responding to the Christian heresy, he has to state some variation of the Christian position to debunk it. That doesn’t make him an eyewitness, any more than you stating that I don’t accept your pretended eyewitnesses makes you a Christ denier.
The bible records that there were over 500 eyewitnesses to Christ’s resurrection. Do you accept them as witnesses? I sincerely doubt you will.
If he was responding to the Christian heresy,
***Then by that early date in history, this “heresy” was already claiming that Jesus was put to death for claiming equality with God. There’s no evidence that this creeped in over hundreds of years. It was being loudly proclaimed by the year AD30-AD35, right out of the gate.
So do you accept that this rabbi was a historical person dealing with his own contemporary issue surrounding christianity at his time? Or does his name have to be written into stone for you to accept historicity?