I disagree, if they had purchased the game legally it would have no effect on Nintendo since they don’t produce melee, and they wouldn’t get money from them choosing to ban illegal copies, plus it’s just emulation of the game which is almost essential to keeping old games alive

Using pirated ISO's and ROM's are illegal and Nintendo are in their right to shut it down. Plus you don't need emulation to keep old games alive, just look at CTGP :P

Nintendo are indeed in their legal right to do so, but them doing this is only disconnecting them from the community that loves their game so much, and also melee never had online on its native hardware so this would be the only way to make it function online