Azeris aren’t Arabs, though. There must be something else going on here.
From reading articles several years ago in the New York Times, I believe I remember that this school was kept open by the personal intervention of a powerful Israeli diamond merchant, originally from one of the now-independent nations of the former Soviet Union, who has direct ties to the Azerbaijan government. The government wanted to shut down the Madrasas and tried to close all private religious schools; the Jewish school stayed open and the radical Madrasas closed.
That's not good domestic politics if you're a Muslim leader.
In other words, this terror plot may have been an effort by the radical Islamofascists to embarrass the Azerbaijani government for personal ties to key Israeli business leaders. Either way the terrorists win: If the government protects the Israelis they get criticized for being un-Islamic, and if they fail to protect the Israelis they face the wrath of Israel.
I'm going from memory here. Others may be able to fill in details.