In the case of battalion level or higher officers, they definitely do not need rifles or even pdw's since that isn't part of their job. It will only get in the way. They would not only have to lug it around as they move from one location to another, but also are kept accountable for that weapon. That is one more unnecessary variable that increases the complexity of their job. Their job is to receive information, observe the battlefield, make decisions and etc, not to fight.
Also, 300 meters is within the effective range of an intermediate round like a 5.56. That is definitely not considered sniping range.