Tell me what you think of the following solution to the discrepancy:
We will go with your version of the story (that the elephanters rebelled as soon as thedude attempted to control them). However, there would also be a sect of elephanters who beleived that the wisest course of action was to submit to thedude's control. This way, the elephanters would immediately fight back as you described, but there will still be a few sympethizers for thedude that remain loyal for ten years, as I described.
I admit that I wasn't thinking about the cannon concerning the Rhoddwr Marwolaeth when I wrote the AM; I just threw that in as an easter egg without giving it much thought. I think the best way to resolve this would be to simply make the destruction of the Elephanter moon non-cannon.