This paper is regarding a conceptual space tether launch system, and states quite plainly that the hypersonic vehicle mentioned is based off a previous Boeing conceptual study (a 7 year-old study at that). I think the way the paper is written is a little disingenuous to those unused to reading technical publications, but the assumption of a supporting system being in operational existence for a proposed conceptual design to have merit is not uncommon amongst these theoretical concept papers. Always check the references to be sure (reference 4 in this case, looks like a conference presentation).