How can I get my companion to not throw grenades at the mosquitos?

On Fallout 4 (on PC) I've given my companion (Hancock) my stash of fragmentation grenades. Since he's got a shotgun, and I've got a sword, I figure he's the better of us to be chucking them. I've taken a level in the 'Inspirational' perk so I don't have to be worried about him injuring me by tossing them too close.

But now my problem is that he goes for the grenades first instead of his shotgun. Just now we were hiking to a settlement and came across a swarm of bloodbugs. I drew my sword and attacked them -- and Hancock threw a grenade.

I mean, seriously. I like explosions as much as the next gal, but they're just glorified mosquitos the size of a large dog. Is there some way to get him to prefer his gun to the grenades? Is it somehow related to the weapon I've given him? He's got a shotgun, which means he gets two shots and then has a slow reload -- I don't recall having this problem when I had him equipped with a plasma rifle in another save game.

Unfortunately the base AI in this game is pretty dumb. The only real consideration it makes is "MOAR DAMAGE MEANS BETTERER".

The good thing about it - no one is more accurate with grenades than AI. The bad thing about it - It doesn't matter if it's a mosquito or a Super Mutant Behemoth - moar damage means betterer.

There are mods out the that can help stem the flow of grenade spam, like this one, which simply depletes their ammo for grenades, but that doesn't really help your situation.

The only other suggestion I can provide is give him a gun that deals more damage than your average grenade, but since they don't have an "armory", per se, they'll then switch from solely using the grenades, to solely using the other weapon.