I've always been on the side of adding a rifle or more significant firearm than a pistol to deployable classes. For example, the M1 Carbine for the US, the Enfield for the Commonwealth & British forces, and the K98 for the Germans.
It's only one more rifle. Hardly overkill. I can't see any imbalance coming from it. Quite the contrary - the change might be benificial, as it would encourage players to use more pickup kits since they can defend themselves in certain circumstances. A player that can stow away his pickup and use a rifle is also a benifit to a squad. Deploy times and other mechanics essentially remove rambo'ing, so I don't see why this can be viewed as a imbalance.
We could be here all day and argue historical accuracy. There's evidence for and against, as illustrated by documented photographs, accounts and other media.