Remember that the 40Ah rating is based on a C/20 discharge rate, which would be just 2A. Drawing 4A would cut that by more than half, to about 9 hours. Not sure why they went as low as 4 hours, unless they are being very conservative.
[Edit]:
Moving on to the second column, where it draws only 1A, since that is less than the C/20 rate of 2A, it sure seems like then you should get close to the full 40 hours out of the battery, even with the 5 minutes of alarm time at 4A. 24 hours seems too low to me.
So you're right - the numbers here don't make good sense.
[Edit2]:
One other thought... a battery capacity needs to be de-rated for temperature effects, too. Although the table makes no mention of an assumed temperature, perhaps they built something other than normal room temperature into this.