Even if SD came back, your Ttar probably couldn't get it. I'd TM to B/C.
There's also a possibility that Rhyperior will get a double rock move, in which case he'd likely take the rock throne from SD Ttar.
Finally, B/C Ttar is really useful now in Mewtwo raids, only a 20% chance of running into FB, so an 80% chance of being one of the best counters.