1) He has no proof - he's just taken some dates, fiddled around with some numbers in a COMPLETELY ARBITRARY fashion, and then when the numbers started to look sorta similar (because he messed around with his calculations), he proclaimed some sort of discovery. He has about as much credit as the Millerites and the Jehova's Witnesses. The Millerites were founded by William Miller, who whole-heartedly claimed that the Second Coming and the Rapture were due in 1843. Thousands upon thousands of his supporters gave away their possessions, thinking that they'd be no need for worldly goods. Well, 1843 came and went, and nothing happened. Miller became a laughing stock - anywhere he went people would chortle and taunt him with: "have you gone up yet?" Other such predictions have been made over the centuries, NONE of them have come true. Many Christians were certain, absolutely CERTAIN that the second coming would occur in 1000 AD. Nope, didn't happen then either. History is choc-a-block FILLED with failed predictions based on incredibly shaky foundations, often involving ludicrous calculations that have no basis in reality. It almost seems that every single generation wants to, for some bizarre reason, believe that they are the last generation or that the end is nigh. They have no reason to believe this, other than vanity - rather than accept the fact that they are just another generation that will disappear into the vastness of history, they want to believe that they are living in "special" times. They are not.
2)I live in Australia, so I will never meet the crazies who believe that the world will end this month. But in case I do, I'm going to shout: "Yo! Where is he? Have you not gone up yet!" And laugh in their face.