I'm not sure they would have pursued it much TBH. It seems an incorrect username match was already a slam-dunk for the jury. Even if the defence had seen that the IP address was in the wrong location, the prosecution would argue they'd use a residential proxy. It'd be hard to prove or disprove, so it'd probably impact the jury about the same as the IP address being totally in the wrong region - i.e. it'd not be the magic bullet to show his innocence.