What he meant about the cycle crashing, was that without fish/crap/food or other things breaking down in the tank that the cycle would stop and be non-existent. Making it like the tank was never cycled in the first place, when using precycled filter media its important to keep the cycle running by adding in a couple fish, throwing in a little bit of fish food, something along those lines.
I do this when starting up tanks, take a piece of pre cycled filter floss, run in the new tank for 3-4 days, put in 3-6 neon tetras and see how they are. I find that neons are great indicator of the tanks health, and a very quick way to just look and see their bright neon shine to show that the tank is cycled/healthy. If they aren't doing so good, aren't showing much or any shine, then something is wrong and most likely not cycled. (also neons are cheap, so I don't get upset if i lose one or two when holding/starting a cycle in a tank)
Another method is to dose ammonia, over the counter ammonia, to get the cycle going. 10ml on day 1, get the filter running. next day 10 ml more, then bump it up to 20-30ml depending on tank size. This will jump start a cycle, mind you not complete it. (fishless cycling)
I find that just putting in a pinch of fish food is a better suited solution as that the bacteria is then use to dealing with fish food vs chemical ammonia.
But everyone has their preferences.