Seems as this is not for security but rather a dispute over payment for using T3 instead of T1
Ryanair may actualy be right too.
TLV has dual pricing srtucture - T3 is more expensive and includes more stuff. T1 is cheaper, and is limited in which kind of flights could use it - LLC centric
The IAA has no interest in running two terminals at this point. They arent operating T3 at anywhere close to capacity. They basicaly said that any AL returning to serve TLV must use T3 at T3 prices. In the past, whenever the IAA closed T1 for some reason - construction or the like, ,AFAIK they moved the T1 airlines to T3 at the T1 prices. Whicg is what Ryanair wants now.