I also received from Vespasian no small quantity of land, as a free gift, in Judea about which time I divorced my wife also, as not pleased with her behavior, though not till she had been the mother of three children, two of whom are dead, and one whom I named Hyrcanus, is alive. After this I married a wife who had lived at Crete, but a Jewess by birth: a woman she was of eminent parents, and such as were the most illustrious in all the country, and whose character was beyond that of most other women, as her future life did demonstrate. By her I had two sons; the elder's name was Justus, and the next Simonides, who was also named Agrippa" (Life 76).
This is no different than ben Zakkai receiving Yavne and other favors from Vespasian. And Josephus lived, and in Judea at that (just like ben Zakkai), as Jews are commanded to do in the OT (e.g., Lev. 18:5: "You shall therefore keep my statutes and my rules; if a person does them, he shall live by them"). The Messiah dream is not worth dying for, in my view, and Fourth Philosophic Judaism (whose driving motivation was messianism) resulted in nothing but fewer Jews (and loss of autonomy), while Josephus had five children and lived to an old age in Judea, and you can't have Judaism without Jews.