command should not contain multiple words. This is the cause of the [ error you see. You should set any flags separately.

Also, you should use pytivo_user to set the running uid, and not daemon -u. See the rc.subr(8) man page for all these magic variables.

Also, you should let the rc subsystem know that pytivo is a Python script so that it can find the process when it checks to see if it's running.

Finally, you should use the idiomatic set_rcvar for rcvar.

Something like this (I'm not sure this is the right Python path):