Whether or not Finkelstein's commentary here merits inclusion I'm not sure, since it would depend on whether or not he has something unique to say in regards to this particular issue, and I'm not sure he does. In regards to F.'s status as a reliable source however, there should be no argument about that. F. most certainly qualifies. He is one of the most high-profile scholars on the Arab-Israeli question, he has received plaudits from other greatly respected experts in the field (see Schlaim's endorsement above, or that of Raul Hilberg who supported his work and said he would be "vindicated" by history), and he has written best selling books on the conflict that have been  praised both inside and outside academia and translated into multiple languages. His book A Nation on Trial was named a notable book for 1998 by the New York Times. His latest book "Beyond Chutzpah" was published by the University of California Press after perhaps the most thorough peer review of any book on the conflict ever. These achievements demonstrate that he is unquestionably a reliable source in Wikipedia terms.

In spite of this however, some pro-Israeli editors have seized upon his recent denial of tenure as a rationale for trying to exclude him as a source on the grounds that this failure has somehow discredited his scholarship. This is simply not the case. DePaul did not question the quality of his scholarship. In fact, it endorsed him as "a prolific writer and outstanding teacher". F. was denied tenure only because someone didn't like his attitude. But there is nothing in Wiki policies that disqualify sources on the basis of some alleged flaws of personality. It's only the reliability of their scholarship that matters, and F. has no shortage of endorsements in that regard.