They were less likely to be affected by the erroneous ruling of the Court. Proof of this can be found by flipping the page. Ben Azai explains that this is since the person who went overseas could not have heard that the Court overruled its previous error. Every Jew is part of Klal Yisorel. Just as our Shul couldn't use two Jews from somewhere else to help us make a Minyan this morning, the effect of the erroneous ruling does not calculate those on whom the ruling had no effect.
Ownership involves both priveleges and responsibilities.
Rabbi Teitz turns staying in America into a mitzvah. I was brought up that exile was a punishment for sins not a reward. But if the advice is wrong and things get rough then they have an obligation to run away to save Jewry. To me this sounds like the all the evils of absentee ownership, the ultimate kibitzer. On the contrary I think Rabbi Teitz's arguments demonstrate why non-israelis should not get involved.