"The writer made it sound like it is the government’s prerogative whether these billionaires should be able to keep their own hard-earned money."  

Actually no, those billionaires are dead and their money is changing hands, and like with most transactions, there is a tax involved, although only if the amount is very very large.  Such is the fee for accumulating a large fortune in the land of opportunity.  

To believe the estate tax should be repealed is to believe in the not so American idea of a permanent aristocracy.