The rule is "No maps identifiably from the Neroxis Map Generator." There are easy ways to identify Neroxis Maps that have had little to no edits to them, and if we can't identify them then they probably meet the arbitrary threshhold of effort. The main point as mentioned is that if it's just a cool seed then the seed can recreate it without using server space and cluttering the vault.
There are internal talks about amending the rule to clarify our stance on using gen as a starting point. That will likely include requiring listing the starting seed and an overview of the changes made in the description, and shifting definition of the arbitrary threshhold of effort over to vault guidelines, for which violations of can only result in the map getting hidden.

