Whether or not a calendar is tabular data depends largely on the culture which produced it, and the duration being handled.
A one-month Gregorian calendar is most certainly tabular data. Culturally, the calendar has been divided into weeks, and the weeks into a repeating cycle of days. Each cycle is typically displayed stacked one atop the next, such that each day in the cycle forms a column, while each iteration of that cycle (a week) becomes a row.
Other calendars, on the other hand, might not be tabular. The Mayan Calendar would be almost impossible to display in a tabular form. The traditional Chinese calendar also has other forms which suit it better. God help us if the Time Cube Guy ever tried to devise a calendar for his site.
Tables have been abused to create non-semantic markup; of this there is no doubt. But that does not mean that tables are inherently non-semantic. Almost everything in the HTML standard has a place and time where it is semantically meaningful (the most famous exception to this being the FONT tag). Tables, too, have their place. The anti-table zealots need to learn this, otherwise (as with this hack) they risk destroying semantics in the name of semantics.
