Mea culpa - as I realized from your response (and the two others), I did not make it clear that 1) this controller is a wireless system and 2) it includes multiple launch capability (not just clustered but also sequenced). Thus (if one reads and follows Stine's book), deadman functionality is pretty much a given.
What I was struggling with (and your post helped me crystalize - thanks) is whether to "cut short" a launch when the current to the igniter has already started flowing. This question is especially problematic for clustered launches as I already described. But I've decided that once the current starts, the launch of THAT particular unit should continue to completion, whereas any others (sequentially thereafter) would be not be permitted to start.