It's very likely that this change would break "Start new session" feature of
KDE which works fine at the moment. While I could live with having it broken
on kFreeBSD, that's definitely not acceptable for Linux where this problem
does not manifest itself.
The bug we are facing here is that kdm starts on vt2 when it's not supposed to
even bother with VTs below 7. ServerVTs=-7 setting in /etc/kde4/kdm/kdmrc
takes care of it (on Linux). However, apparently ServerVTs does not work on
kfbsd for some reason (nor it's present in default kdmrc). Finding that reason
would be the real fix and I will look into it later today/tomorrow. It could
be as easy as #define which does not cover kfbsd (I hope).