I thought it means exactly that for X you need to run xenodm.
But if you don't want to run it by default you can use "doas rcctl start -f xenodm" to start display manager when needed.
I was incorrect: It appears that you do in fact need root to run startx now:
(quoting the faq page for upgrade65):
Xorg(1). The Xorg binary is no longer installed setuid, so startx(1) can no longer be used by non-root users. The xenodm(1) display manager has to be used instead.
From a security standpoint this makes sense, of course, but how are you supposed to deal with a half-desktop-half-server system?