I’m not sure if we are on the same side, and honestly in this case it doesn’t matter, since you are right: a corporation only has to care about the externalities as much as they are forced to and not even an inkling more than that.
People who think that an enterprise in a free market will respond to any other force than economic force are wasting activism time that could be better used elsewhere.
If you want a corporation to stop performing a socially harmful business, you need to make that business unprofitable.