Pat Perriello, I'm so embarrassed for you. Either you didn't do your homework for this article, or you were the wrong choice as the author.

1. "Two rabbis wrote a provocative article": first, name them; second, set the context: not all rabbis think the same. Rabbi Poupko, for instance, is an Orthodox rabbi, the descendant of a long, distinguished rabbinical lineage, the Poupko rabbis, &  the Twersky Chasidic dynasty. Wikipedia.com them & their families.

2. "At first blush it seems they are saying there is no role, and Christians disrespect Judaism by trying to celebrate this Jewish tradition."  
At second blush, too: that's exactly what they were saying. Exactly.

3. "The notion appears to undercut efforts at greater ecumenical understanding."
Sir, it is not a "notion". It is a thoroughly developed, documented position.  If you had researched these two rabbis, you would have realized that "ecumenical understanding" is not the goal of their essay.