how to replay log of a fs that has no log: is this supposed to work? SW Defect?

[Linda Walsh]

Linda Walsh wrote:
(blah blah blah)...

or more specifically:

xfs_freeze -f /home/.snapdir/\@GMT-2012.10.04-03.06.17
Ishtar:/# xfs_ncheck /dev/Home+Space/Home-2012.10.04-03.06.17  

    ERROR: The filesystem has valuable metadata changes in a log which needs to
    be replayed.  Mount the filesystem to replay the log, and unmount it before
    re-running xfs_ncheck.  If you are unable to mount the filesystem, then use
    the xfs_repair -L option to destroy the log and attempt a repair.
    Note that destroying the log may cause corruption -- please attempt a mount
    of the filesystem before doing this.
    must run blockget -n first

ok -- lets mount/umount it:
Ishtar:/# mount -o ro,nouuid /dev/Home+Space/Home-2012.10.04-03.06.17 
/home/.snapdir/@GMT-2012.10.04-03.06.17
Ishtar:/# umount /home/.snapdir/@GMT-2012.10.04-03.06.17
Ishtar:/# xfs_ncheck /dev/Home+Space/Home-2012.10.04-03.06.17  

    ERROR: The filesystem has valuable metadata changes in a log which needs to
    be replayed.  Mount the filesystem to replay the log, and unmount it before
    re-running xfs_ncheck.  If you are unable to mount the filesystem, then use
    the xfs_repair -L option to destroy the log and attempt a repair.
    Note that destroying the log may cause corruption -- please attempt a mount
    of the filesystem before doing this.
    must run blockget -n first

---
Um... looking at the above it would appear that I froze a fs.
ncheck claimed the freeze didn't result in the logfile being written being put
into a consistent state, but said to remount the fs to allow it to play then
umount...

So... did that.
Log file is still in a corrupt state.

Am I wrong in assuming that doing xfs_repair -L to destroy the log on this
dev, might be a bad thing to do and might screw up it's "Origin" file
system (i.e. the current 'live' /home partition)?