This could have easily been proved by the Jewish clergy if it was made up because the tomb owner was a member of the Sanhedrin. There is no record of anyone contesting that Joseph of Arimithaea was not a real person or that he let Jesus be buried in his tomb.
No.
Once again, you do not realize the context of the time.
First of all, the Jewish clergy? They did not care about Christianity. It would be until at least 80 C.E. that Christians would be expelled from the Synagogues.
If they knew about Jesus at all, they probably considered him as a local folk hero that was killed by the Romans for his defiance against their occupation.
But really, NOBODY cared about Christians or knew much about them. At that time (until the end of the first/beginning of the 2nd century) they were considered a couple of handful of lower class nutties. They had a trouble making leader, he was dead, problem solved.
It would take decades and hundreds of miles until Christianity rise up to warrant making any sort of effort. Decades that were interrupted by a major civil war, the destruction of the temple and all the religious and sociological turmoil that came with it, and the exile and executions of thousands of Jews.
By that time, the only witnesses that cared enough to remember anything about Jesus were the Christians. And, even then, the contradictions between all the Gospels (and I am including the apocryphia) show well how hazy these memories were.
When the Christian started to be significant enough to warrant looking into them, the only people that had recollection of the events, kept note and transmitted memories, were the Christians and the Pagans, having nothing better to substitute, accepted most of these claims, unless they clashed enough with their own beliefs to arise scepticism.
Let me give you an example. Who founded Scientology? L. Ron Hubbard. What are the 'sacred texts' of Scientology? The books of dianetics. Who wrote them? L. Ron Hubbard.
How do I, and probably know that, because Scientologists, or people reporting Scientologists words, told us so. Did we investigate ourselves? Nope.
Now, the Scientologists also have claim about body Thetan and volcanoes and DC9 and such, and these we reject, because they clash enough with what we know of the world, but other believable facts, we do accept, they are credible enough.
And, that's us, leaving in a relatively rational and well informed society, with the actual information available somewhere and reasonably easy to find.
Imagine being in the context of the first century Eastern Mediterranean and being separated from the alleged events by several decades and a major local civil war. The siege and burning of the city, the execution of thousands of civilians and the displacement of thousands others. That'd make investigation extremely difficult and particularly not warranted in the social context of the time.