No, that's probably just by convention. If it's strictly an input then both directions are just the same in terms of safety. It's just sometimes more convenient to only pull things down or up and have a resistor provide the opposite pullup/pulldown current.

Maybe it was chosen because the "high" voltage isn't specified and the standard might say: "Pull down to GND to activate, leave open to keep card off." Then you don't have to think about the internal logic voltage of the circuit, you might fry the card if you pull up to 3v3 if the logic input is only 1.8V tolerant.