There really are people who genuinely believe the whole argument is whether some guy was some thing. But the Messiah in Judaism is not an inherent quality of a person to be detected or disproved through an empirical test. The Messiah, by definition, is the one whom Israel accepts as their Messiah. Thus, the rejection of a given individual by the collective entity of Israel is not a “proof”that he was not the Messiah, the rejection itself - as the normative decision of the Jewish nation - is what constitutes him as non-messianic. This is why Maimonides rules that the Messiah is not required to perform signs or wonders; he must simply be accepted by Israel, and if, upon that acceptance, he achieves the historical and physical redemption of Israel, that outcome itself constitutes him as the Messiah. If he is accepted and acts, but fails to achieve that redemption, he is not a false messiah, but a failed messiah - a historical candidate who did not fulfill the task. But if he is rejected by Israel from the outset, he is a false messiah by virtue of being rejected. Furthermore- if Israel rejects every candidate, and the historical redemption of the nation is achieved without any individual leader, then the view of Rabbi Hillel - that Israel has no Messiah to come - is what becomes constituted by Israel. And of course, there is also the non Halakhic messiah who is always coming - upon whom our Sages said: “Let him come, but after I die”