The only studies that I looked at actually talked about the healthy soldier effect and this way of thinking that it should be a protective role. But I think what you're talking about is the huge impact it has on the person who does feel that they are healthy and fit, and in fact healthier than the general population. The way their life has been up until the point of injury can really have a severe impact. The injury can have a bigger impact on someone like that.
So I guess in that case, in the example you're giving, the healthy soldier effect may not be protective.