You've left out the context of that quote to invert what the sentence actually said. Fayzullin's entire statement was:

    "[...] If you see that your .NES file DOES NOT match any
     of the ones found online, it is likely to be their own ROM dump.
     I have cut the ROM content out of the Wii file
     you sent me and it indeed matches the .NES file found online."

> it does not appear that they downloaded a Mario ROM

That is literally the opposite of what Fayzullin said.