I would say it is very dangerous to make a trigger volitile like that. Might i suggest using a toggle of some sort; turning off the trigger when you want it "disabled." The triggers that are created within the source are going to be there, weather enabled or not. Also: once the map changes all triggers will be deleted because AMXX isn't persistent, unless done through a file. If you're that worried about lag from users creating so many triggers...i'd suggest only allowing a single user to create so many (1 or 2) that way you'd have a max of 64.
But then again.....i'm just spurting crap. I don't know exactly what you'er trying to do. Code might help me.