Messianic Claimants and Historicity

[ConsequentAtheist]

First:

There was an Egyptian false prophet that did the Jews more mischief than the former; for he was a cheat, and pretended to be a prophet also, and got together thirty thousand men that were deluded by him; these he led round about from the wilderness to the mount which was called the Mount of Olives. He was ready to break into Jerusalem by force from that place; and if he could but once conquer the Roman garrison and the people, he intended to rule them by the assistance of those guards of his that were to break into the city with him.

[Flavius Josephus, Jewish War 2.261-262]

This is pretty serious stuff. In fact, it's the stuff that history is made of. But, to the best of my knowledge, there is no other historical evidence for the "Egyptian" save for a brief reference by Luke (see The Reliance of Luke-Acts on the Writings of Flavius Josephus).

In fact, there is much history that we tend to accept with little more that circumstantial/anecdotal evidence. So, my question to mythicists is this: is it reasonable to expect that the leader of a small Jerusalem cult would be better attested than someone apparently ready to move 30,000 men against that very city?