I see that in the Quatre Bras DLC it says, "Removed the ability for cavalry to capture and bring enemy guns into action."
Yes, but it still doesn't do what you want to simulate. If cavalry captures artillery now they are simply removed from play, guns and all. And the cavalry unit still gets the points for capturing the guns.
The best way to protect artillery from cavalry is to place the battery between two infantry squares, with the squares out in front ahead of the guns. This does two things, first, by spacing the squares out so that the guns are in between them, the guns maintain an effective and open field of fire. And 2nd, by moving the squares forward of the artillery cavalry cannot charge the guns. This is because there is no way to choose a specific target with cavalry, it simply charges the nearest unit in range. If the squares are out ahead of the artillery, they will always be the nearest target to the cavalry, hence the cavalry cannot charge the guns. The guns will however plow them with close range canister fire.
You can see this technique demonstrated in my video on the scenario "Mont St Jean: Sabers vs. Bayonets"