in the case of the stako bottle i don't know if loctite is used or not. the reason it is not advised for other bottles is that the bottle threads can be ruined when removing the reg. in the case of the stako bottle, you won't be getting it retested, so unless you need the reg removed for a flight it shouldn't make any difference.
I personally have never loctited my bottles, and have never had any problems either so i would advise against. as long as the reg is on tight enough the pressure of the air will keep it secure.
hoep this helps, or again i could be talking sh!te........................