It's my understanding that Equifax is a multibillion dollar org. (Something in the order of 17 billion USD). Since Struts is a major part of their business infrastructure one would expect a contribution to the Struts project and other software they rely on. They could spin it as "Social Responsibility" too.

In retrospect it seems more cost effective to do so too, even if Equifax manages somehow to pay only a few hundred million dollars.