I find it quite unlikely in the midst of what the U.S military needs to do now a soldier would take the time to vent on HN. But sure, if that is the case I guess he earned the right to vent; still slim (borderline zero) chances of him dying even if he is U.S military.

People who were actively told that they wouldn't be deployed ended up being deployed in very recent history, they could be sitting at home reasonably worried about that.

Perhaps they're a national guardsman, for example?