That is a potential nefarious application, yes.
But to manipulate the love circuitry specifically for a cause, you'd either need a very complex optogenetic assembly...
or just go the easier way and implant an electrode into the brain of the soldiers that stimulate the reward system positively when the nanocomputer hears talk of the "mother country", or sacrificing yourself life for it, and causes anger when hearing about the enemy.
It's very close to Pavlovian Conditioning.
I don't think they'd need optogenetics... North Korea could literally do this now if they thought they needed to reinforce their already brainwashed troops.
I do believe "do it for your country, not the money" is pretty much how it already works in dictatorships that have a firm grasp on their citizen's lives and minds. No need for fancy new tech.
Of course you are right. Then again, apparently the heat of the battle makes the soldiers with some conscience get the heck out asap, some in surviving cowardice, others shocked and panicked. The step further to complete mission regardless of one´s life, very well could be accomplished with a little software/hardware combination. I mean one thing is creating super expensive supersoldiers and another cheap hardware addons for mass soldiers with clear beliefs that is not the addon, is them who are convinced.
But stop with all this war bullshit, the applications are so wide that the possibilities really depend more on the imagination to look for an specific application.
And thanks for the post, it should make all of us think a little more about what is really going on in the world.