Some updates.
Rebooting after kickstart, the vnc screen shows
Booting from Hard Disk... GRUB
It's hung there. This makes me think that grub wasn't installed correctly. But this looks normal:
# file -s /dev/dm-6 /dev/dm-6: x86 boot sector; GRand Unified Bootloader, stage1 version 0x3, boot drive 0x80, 1st sector stage2 0x882ee7, GRUB version n.m; partition 1: ID=0x83, active, starthead 1, startsector 63, 20964762 sectors, code offset 0x48 #
Next, with some kpartx magic, I'm able to mount the single partition on the lv that provides the vm's disk device and find that /boot is all kernel pieces. Modules are missing, too, so the kernel didn't get installed. Manually extracting the kernel rpm and putting the pieces into place does not help, even if I build an initrd.