Two things... 1.) It is not always a bad thing that children call their stepparents "mommy" or "daddy" if it is the child's choice, and they understand the difference. My stepdaughter started calling me mom when she was 4 and I wasn't about to tell her she couldn't. I feel it is just as wrong to tell the child, "you can't call me mommy" as it is to tell the child, "you have to call me mommy." Both are wrong and confusing to the child. Let the kid decide!
2.) There are some people in the military who have no chance of deploying. My husband is one of them.