Pardon my skepticism. The death rate involved here is about 1 per 1000 per annum. That doesn't sound like an unusual death rate for men in their twenties and thirties to me. As for the 28% applying for benefits: well, either you believe 200,000 troops were unknowingly victims of CBW during Desert Storm, or you believe it is perfectly possible that none of them were, and the numbers need have no relation to any underlying "Gulf War Syndrome" at all.
So, the quoted figures are not out of the ordinary at all. OTOH, soldiers are particularly fit and healthy -- but on the other other hand, may be a bit more prone to what really kills most men in those age groups -- accidents, homicide and suicide -- all testosterone fueled.
You could do some really sophisticated analysis, trying to filter out those kinds of causes, etc. But, it sure doesn't look like a death rate that is in any way unusual, on first look.