'ro' option in fstab not recognized?

Hi. I must be extremely stupid. I have this in my fstab

/usr/local /usr/j/usr/local nullfs ro 0 0

but /usr/j/usr/local still appears to be mounted read-write.

Oh wait, I guess this is also already covered by PR 100164.

Line 197 of sys/mount/mount.c explicitly adds an option "noro".
Looks to me like this makes it impossible to mount *any* file system 
read-only, except by explicitly passing flags to mount.
Surely this is not what fstab was designed for? :)