Your cynicism is somewhat warranted, but slightly misplaced.
Facebook is doing this because not doing so would be really bad for business: i.e., it would threaten the user experience of the site. People would either quit Facebook, spend less time on it, severely tone down or alter their usage of it, or create fake profiles for work. Any or all of those things would be a big detriment to Facebook. So taking a stand on this issue is both good for business and good for PR.
Facebook is doing this because not doing so would be really bad for business: i.e., it would threaten the user experience of the site. People would either quit Facebook, spend less time on it, severely tone down or alter their usage of it, or create fake profiles for work. Any or all of those things would be a big detriment to Facebook. So taking a stand on this issue is both good for business and good for PR.