Upon casually looking around for actual i435 gear and not finding any of it, I've come to the conclusion that they probably placed the item level range of this fight (i430-435) specifically where it is to act as a sort of equalizer.

Yes, you can potentially join this fight as a fresh 80 with all i430 stuff; it may not be as high level as the more experienced players who will have stuff all over i435, but this means you will get materia boosts to help bring you to the level of the i435s.