Yes that is a claim they have made, but unless they show up in probate court to defend that position, they will do what the judge orders them to in a default judgement.
Hopefully your family won't have to test it for a long time then :-)
Please don't state something as a matter-of-fact if you don't know it to be true but just merely believe it to be true. Otherwise please link to an instance where a probate court has ordered it with a successful outcome.
It seems like a novel idea and I hope someone tries it and posts about it.