When booting into single user mode by appending the runlevel 1 to the kernel command line, openrc will start boot services like localmount, then switch to runlevel 1 and terminate these services again. I would understand rc not starting these services, to provide a minimal system for maintainance in order to avoid problems. Sysadmins could then start services themselves. I would rather expect rc to start boot services at all times, and leave them running even in single user mode, the rationale being that for really troublesome cases, the admin is more likely to set some recovery shell as init process and not use rc at all. Either of these solutions would make sense, but the current behaviour makes no sense to me.
Oddly enough, this is correct behaviour :) sysvinit makes a distinction between single user and runlevel 1 For the behaviour you desire, append either single or s to the kernel commandline OR comment out the line starting "rc::bootwait" in /etc/inittab
Not a bug.