What does "Maximum Input Current" in a data sheet mean?
For the example given, it's the maximum current the device will draw when:


  \$V_{IN} = V_{IN, min} \$
  \$V_{O} = V_{O,set}\$
  \$I_{O} =I_{O,max}\$


For the most part, specific test conditions are given for how maximums and minimums were measured. Holding the outputs steady, if you were to increase the input voltage, the input current would drop. So, assuming you aren't going to violate any of the other inputs or outputs, the current should not increase above the specified value. 

This most closely matches option two that you've given. You should design to actively maintain the voltage specifications and the current will behave accordingly.