however you want to defend it:

NA players got a free transfer away from the EU servers when they relocated the EU servers. this relocation leaded to higher a ping for NA players, wich were playing on EU servers. these NA players have known from the beginning that they are playing on EU servers.

now EU players don't get a free transfer away from the NA servers when they relocate them. this relocation will lead to a higher ping for EU players, wich are playing on NA servers. these EU players have known from the beginning that they are playing on NA servers.

it's exactly the same situation. NA players got a free transfer, EU players don't.