Every entail is different, it all depends on how it is written up in the Rules Patent. As Mr Elliot has been estranged from the Kellynch Elliots all his life, he probably has no idea of the exact wording of the entail. We do know that not all of the Elliot property is entailed, for Sir Walter refuses to sell off any portion of it when faced with the necessity of retrenching. So I believe Mr Elliot is simply engaging in hyperbole here, exaggerating in order to show his disdain for the title and estate.