Thing is there are three issues here.

1. Divinity has been playing with T1 Eden 1 prep, and it is regardless of what anyone says the default ranked ruling system used on RPG Guild, Rilla said so, and he's the president.

2. A ruling has been made using T1 Eden, assuming the one prep system was in play.

3. Changing the rules now provides an unfair advantage to Dazsos, because he is the first to benefit from a system that wasn't in play until this point. If you were going to use a multi-prep system (I have no idea how this works though, if everyone can use as many 'preps' as they want preps are meaningless, as they work as an external balancing system like dice rolls. Multi-preps is basically the equivalent of letting everyone roll as many dice as they want, AKA pointless.) you had to hash that out at the start.

Which is why to change the rules now I believe would invalidate this fight as a ranked match, though I'd have to get Rilla to look at it to know for certain.

Also, the implications that high tiers have more preps is sort of a fallacy, if anything higher tiers can carry out more spectacular abilities without the need to prepare anything at all. If you want to have your spells require preparation that's fine, but only one of them should get any additional bonus from it. The whole point is that you place all your focus into one powerful attack and that's why it defeats an opponent's unprepared defence. That argument falls apart if you can prepare multiple powerful attacks at once, because your supposed to be the same tier as your opponent, so surely they can just do the same.