It’s bad enough that one of HRC’s followers should regard Barack Obama’s decision to challenge Her Inevitability for the Presidential nomination as presumptuous. (That’s the way I would have characterized her apparent conviction that the nomination is hers by right.)
But what’s intolerable is that (unnamed) person’s apparent belief that the substantive of “presumptuous” is “presumptuousness,” rather than the shorter and more euphonious “presumption.”