Might want to point out to him that this is nuts stuff based on one Mayan calender that ends in 2012. They made other calenders that ended far, far, far further in the future. They also didn't think the end of the calender meant anything other than they'd have to make a new one. This whole thing is a weird mix of Mayan calenders being mixed with Christian belief in the end of the world, something that most ancient religions and peoples didn't believe.
Also, ask him why he thinks some ancient Mayan calender makers would have information about this? They just studied stars closely so as to make accurate calenders, which are very useful to civilizations for timing things like crop planting and such.