The methods of archival and transfer used in the vNES software can be reasonably argued under the premise of fair use, given the following:
The purpose and character of the use, such as if the works are used for commercial or nonprofit purposes.
Since our inception, vNES has been an advertisement-free public website which does not require subscription.
Question is - who has reasonably argued it?? They seem to put up their argument in what you have posted, but has a Corp challenged it to date - it would appear not.
They are proving they are not for profit a number of times in there and effectively arguing as such they are expemt from copyright laws (apparently) - tread careful with this one is all I would say.
A lot of the above seems assumption on their part and not legally challenged, remember P2P started like this and look what happened to those guys who got caught big!!