In Chapter 11 of All Quiet on the Western Front, why is the orderly "mystified"? Baumer would be mystified since he doesn't know Kat was shot in...

In Chapter 11 of All Quiet on the Western Front,
the orderly's being mystified has nothing to do with the fact that Kat is
dead.  The narrative reads, "The orderly is mystified.  'You are not related, are
you?'"  Paul has agreed to take Kat's paybook and his personal effects.  It is obvious
that Paul is distraught over Kat's death--he has just spent the last few moments in
denial over Kat's death.  Paul was incredibly close to Kat during the time they spent in
the war, and Paul regards Kat as a brother.  Paul treats Kat as if he were family, and
the orderly is mystified by the close relationship that is revealed by Paul's reaction
to Kat's death.  The orderly sees people die regularly--similarly, Paul has seen men die
regularly.  However, Kat's death is not an everyday event--for Paul, the death of Kat is
the end of his hope.