I did not intend to imply you can't restore the DB from the target server.
What I meant is that you cannot restore client files from the target server.
You have to get the source server up and running again.

It's really no different from any other DR situation.  If you lose your
primary TSM server, you have to go and get the tapes out of the vault and
reload the DB before you can do client restores.  With server-to-server,
your vault is electronic, so you don't have to physically go and get the
tapes, the data comes over the wire.

But you STILL have to reload the DB of the source server.