I think twistys are fine under water. As long as you maintain the o-ring now and then, and twist slowly. My dive lights are twistys. I have taken both the lumintop worm and maratac cu freediving with no problems (exept the worm was slippery and slipped out of my hand once).
Most of the aaa lights i have played with handles water fine. Both clickys and twistys. My lf2xt have survived the washing machine.. 3 times...
Have dunked the preon 1, preon2, p0, tains ti p0 with no problems.
O-rings can handle a lot of pressure. Im impressed over the o-ring in my old pre charged pneumatic air pistols. I can still pump them one day, and shoot the next. One well lubed old o-ring holding all that pressure.
Hope the torpedo arrives soon