If we substitute any other group for the word "Jewish", we would rightly condemn this as segregationist/racist/xenophobic speech. (i.e. - Don't dilute the white race, Don't dilute our Chinese blood. Don't marry a jew and foul up our catholic heritage.) Why is it acceptable in this case? Because being Jewish should be treated differently than any other group?
Ofir Akunis officially replaces Danny Danon as minister of science, technology, and space (Haaretz)
from the article: Jewish extremists to model Bar Refaeli: Don't marry DiCaprio