His company is very large. He owns the Dallas Mavericks basketball team and HDnet, along with a bunch of other smaller things. Plenty of money for lawyers to go after.
. . . and, as he pointed out, in some jurisdictions at least it doesn't have to be someone within the company suing. A competitor could sue, or some ridiculous do-gooder who can't stand to see people "exploited" (like some of the people in this discussion, evidently).