You obviously spoke to a DL agent in the U.S. and most of them are totally incompetent about AF affairs. They likely thought that TLV was served by a wide-body plane equipped with the new J cabin, while it is served by an A320 with the EU-style C cabin.
For your other questions, I have to say that I'm quite confused.
- for the middle seat seating in C, I have never seen that. Question for you : where was the curtain (after which row)? Approximately of course. The curtain is dividing the C and the Y cabin. Ahead of the curtain, there is no reason to have people seated in the middle seats. AFAIK, TLV flights usually get quite a significant number of rows of C seats (4-12).
- for disembarking, as other have said before me, AF usually blocks people in wide-body planes but not in narrow-body planes and this is is useless in those planes, as you disembark usually only at the front and the C cabin is at the front...