It can't open the initial console. From Documentation/devices.txt:
The console device, /dev/console, is the device to which system
messages should be sent, and on which logins should be permitted in
single-user mode.  Starting with Linux 2.1.71, /dev/console is managed
by the kernel; for previous versions it should be a symbolic link to
either /dev/tty0, a specific virtual console such as /dev/tty1, or to
a serial port primary (tty*, not cu*) device, depending on the
configuration of the system.

What you can do is, for example, is remake /dev/console
as major 4, minor 0. (rm /dev/console ; mknod /dev/console c 4 0);
while this is the old behavior and won't be include in RH,
it should allow you to boot both kernels.