I looked into this. My interpretation was that "suing" is just a way of formally settling and finding the true entitlement people. Mark wants to pay more people than he needed. Even if they didn't know about it, the process helps those to claim they have rights to the land from a old law. So people that never knew they were entitled to some of this land are going to be paid a lot more. The news just loves to say mark is suing poor people.
Not a big fan of Marks work but he could have done the minimum and let those that know about this old law sue him in court, settled for far less or tie it all up and keep all the money. He wants to pay so why not let him give away more money.