I think that the folks at Lockheed and the F-35 program office were pretty desperate to get the Israelis in as a customer for the JSF, as evidenced by the facility with which the IDF/AF has been able to incorporate indigenous systems into the aircraft:

The Israeli air force’s Lockheed Martin F-35 stealth fighters will be armed with a mix of US- and Israeli-made weapon systems, sources have confirmed.

“At least one main weapon system” for the nation’s conventional take-off and landing F-35As will be of Israeli origin, sources related to the issue said on 17 April. The Israeli air force has previously expressed its wish to equip the type with a nationally-developed new-generation air-to-air missile.

………

While the first batch of aircraft will carry the integral electronic warfare system being supplied under the Lockheed-led Joint Strike Fighter programme, it is expected that this will later be “enhanced” by additional units developed in Israel.

You’ll notice that none of the other customers, or for that matter the partners in the development program, have had this sort of ability to integrate their own systems into this.

Basically, the market dynamics are such that the if the Israelis are not willing to buy a US aircraft, it would seriously hinder other foreign sales, so they got some special considerations with regards to integrating their own systems.