Well, the Globe's refusal to run the statement sorts well with their decision to publish this piece by Yossi Klein Halevi, which concludes with this attack on unnamed "detractors":

Ironically, those among Israel's detractors who turn every Israeli act of war into a war crime and subject the Jewish state to a level of moral judgment not applied to any other nation are acting in the worst interests of the Palestinian people. For by deepening Israel's sense of siege, they help empower the same hard-line forces they deplore.

While I understand Zusken's points above, it is clear from Halevi's op-ed that "references" and "proof" are of little interest to the Globe's editorial board, since Halevi makes several claims that would not withstand five minutes of Googling, let alone a rigorous fact-check.

So, while one might wish for more specifics in any piece of writing, the lack of them in the text Unionist has provided is very unlikely to have been the reason for its rejection by the Globe.