There is no reasonable doubt that the domain used is for piracy and the defendant knew as much.
"Beyond a reasonable doubt" doesn't mean you can just say "no that's not true" about anything and have it not count. It's beyond a reasonable doubt, not beyond any doubt. It's not reasonable that this tracker address was gotten from a Linux ISO. Perhaps the defendant could claim they got it from a list of trackers, but they already admitted they didn't, so that's not reasonable either.