Doubtful, Gulf View rock is apparently shipped VERY well and people report little die off occurs... However, the theory is, when you introduce that rock, it should be sufficient to "instantly cycle" your tank... Meaning, it can process the ammonia from any die off on itself, as well as a bioload you add to it... Myself, I don't consider that a "cycled" tank, but I'm probably arguing over terminology rather than the chemical facts of what is going on... Same concept of taking a biowheel from one tank and using it on another... No, it isn't cycled, but yes, it can handle a bioload...
Confused yet? hehehe
Oh big brains, paging the big brains...........!