  It is claimed in the above paper that, if time travel were possible, quantum
propagation would prevent classic time travel paradoxes by establishing
consistent loops; an example circuit is used to demonstrate such a loop. It is
argued here that established loops are not the framework in which the classic
paradoxes arise; rather they arise via the establishment of a concrete initial
history in which no disturbing time travel is allowed and then disturbing that
history via the launch of the time traveller. It is shown that, operated in
this two-pass fashion, if the first forward evolution of their circuit produces
a definite triggering of a backwards time travelling state, the re-evolution
thereby engendered may be organised so as to prohibit the triggering of this
state, thereby creating a classic time travel paradox.
