It has come up before such as here
but no worries or harm in raising it agin as we get closer to the damp squib.
As for why it won't be an issue, well our own calendar runs out every 365 days or so and nothing happens when it ends, this Mayan thing is somewhat similar, the calendar just ran out and needs a new one.
There are also no expected issues that they could have been aware of but we have somehow missed, even a rogue planet would be quite visible long before it crossed paths and there's nothing there. Or the mooted cataclysm is impossible, like dire effects of a planetary alignment or the planet reversing its rotation whilst the crust spins along the old direction of rotation.
This is why there has been a recent reappraisal of the source so that they may move the doomsday date to another far off point and not look foolish as the terrible day comes and goes with nothing happening.
Hope is but the first step upon the road to disappointment.