I've created a reusable workflow template associated with a content type and configured Workflow Settings to conditionally start when an item is modified (i.e. workflow should only run if previous value of a column was "X" and current value of a column is "Y").  However, if I try to add that workflow template directly to a list, or to the associated content type in that list, under Start Options the selection for "Changing an item will start this workflow" is greyed out. 

Is it not possible to add a reusable workflow template with a conditional start?  It seems strange to me that I was able to create the template with the conditional start if I'm not able to then add it as such.