Don’t forget that criminal convictions take time. Months of time. By the time your rapist is caught, tried, and sentenced, you might have very well had their child already. Criminal convictions are not the neat and tidy SVU “oh we caught him and he’ll be tried and sentenced within two weeks” shtick.
If you had actually ASKED the Sioux of the Black Hills about this, you’d know they’ve told pretty much everyone “yeah we don’t like Mt Rushmore, we don’t like Crazy Horse’s relief carving either, but we think destroying them is more disrespectful than just leaving them to fall apart on their own.” Like, this isn’t an uncommon thought. It’s just more complex than “blow them up”.