Transmission cases don't explode. The parts inside of them can, however.
And for the record, a local racer exploded a stock high gear drum in a T400 through the lights at our local track recently. Exploding drums isn't just a torqueflite problem.
If you are implying that you need an sfi case to contain an explosion, that is certainly a valid argument, but if the transmission is built properly and has billet drums the chance of having an explosion is practically 0%.