I have always thought that, since the roads are still closed to the populace, the soldiers are enforcing this law by preventing people from getting to them. Assuming that Severian's dream in Saltus is a valid recollection of the events that happened at the gate, the soldiers were not attacking any creature, but rather attacking the people exiting the gate and scattering them out. My reasoning behind this is that why patrol all of the roads, all of the time, when you could stop the traffic at it's source.
I also find it interesting that Wolfe uses the same theme (of perfecting one's self through changes made to another, or later, version of the present self) of "The Fifth Head of Cerberus" in TBotNS. If this was true then does Severian, more precisely Severian2, go back and make changes to himself and/or events in his earlier life? After all, if Severian1 attained the New Sun status and still went back and made life easier for ,essentially, himself (or Sev2, if you prefer), then Sev2 can and will do the same.
Xury