Erm right, and this comet that we weren’t told about, no amateur astronomers saw it I suppose. Despite the fact that comets that don’t even pass into the range of the Earth’s orbit can be seen with the naked eye (e.g. the recent Comet Macholtz).
What your saying is simply wrong, if a comet really was going to hit Earth, and ended up being a near miss, there is no way we wouldn’t all know about it, because aside from all the conspiracy theories the NASA/CIA etc etc could not stop me from looking up at the night sky and viewing such a comet through a telescope.