There are 2 reasons he might be considered persona non grata by the government. First, his views are extremely critical of the Occupation & the intelligence services are notoriously unwilling to engage w. ideas they consider anathema. Second, since Arens is an expert in computer security related to terrorism issues they might feel that sharing information w. him might compromise Israeli security. This is just a surmise on my part since, thank God, I’m not an Israeli spook. But if the Shin Bet can consider Azmi Bishara an Arab spy, then I have no doubt the Mosad could easily consider Arens a security risk. It would be a preposterous supposition, but one I’m fully confident the Mosad might make given their past history.

I would think there is so other reason for it.

No. There is one critical diff. bet. Gordon & Arens. Arens is an expert in the extremely sensitive field of computer security & terrorism. At the conference, he would rub shoulders with Mosad & IDF intelligence analysts who are known for their extremely close-minded & intolerant views both regarding free expression of ideas & the Palestinian “menace” to Israel. In their close-minded universe, contact w. Arens would somehow lead to compromising of Israeli security.